HTTP3/QUIC Unsupported (Document loading timeout)

[tunloop]

Describe the Bug

After the upgrade to 24.04.13.2-1, documents no longer open and timeout.
Curl from clients succeed with OK received.

Initially I was very confused, as just with warning logs, there was a very mysterious [380B blob data] on its own line...

I am not sure if the SSL error is a red herring since the log after clearly indicates coolwsd was able to decrypt and receive an HTTP request. (or why the SSL errors are even happening??)

(Please complete the following information)

• Collabora version: 24.04.13.2
• OS and version: Debian 12
• Browser and version: Firefox 136

Server config

<!-- -*- nxml-child-indent: 4; tab-width: 4; indent-tabs-mode: nil -*- -->
<config>

    <!-- For more detailed documentation on typical configuration options please see:
         https://sdk.collaboraonline.com/docs/installation/Configuration.html -->

    <!-- Note: 'default' attributes are used to document a setting's default value as well as to use as fallback. -->
    <!-- Note: When adding a new entry, a default must be set in WSD in case the entry is missing upon deployment. -->

    <allowed_languages desc="List of supported languages of Writing Aids (spell checker, grammar checker, thesaurus, hyphenation) on this instance. Allowing too many has negative effect on startup performance." default="de_DE en_GB en_US es_ES fr_FR it nl pt_BR pt_PT ru">de_DE en_GB en_US es_ES fr_FR it nl pt_BR pt_PT ru</allowed_languages>

    <!--
        These are the settings of external (remote) spellchecker and grammar checker services. Currently LanguageTool and Duden Korrekturserver APIs are supported, you can
        set either of them. By default they are disabled. To turn the support on, please set "enabled" property to true. It works with self hosted or cloud services, free
        and premium as well. The "base_url" may be https://api.languagetoolplus.com/v2 if the cloud version of LanguageTool is used. Please note that your data in the
        document e.g. the text part of it will be sent to the cloud API. Please read the respective privacy policies, e.g. https://languagetool.org/legal/privacy.
    -->
    <languagetool desc="Remote API settings for spell and grammar checking">
        <enabled desc="Enable Remote Spell and Grammar Checker" type="bool" default="false"></enabled>
        <base_url desc="HTTP endpoint for the API server, without /check or /languages postfix at the end." type="string" default=""></base_url>
        <user_name desc="LanguageTool or Duden account username for premium usage." type="string" default=""></user_name>
        <api_key desc="API key provided by LanguageTool or Duden account for premium usage." type="string" default=""></api_key>
        <ssl_verification desc="Enable or disable SSL verification. You may have to disable it in test environments with self-signed certificates." type="string" default="true">false</ssl_verification>
        <rest_protocol desc="REST API protocol. For LanguageTool leave it blank, for Duden Korrekturserver use the string 'duden'." type="string" default=""></rest_protocol>
    </languagetool>

    <deepl desc="DeepL API settings for translation service">
        <enabled desc="If true, shows translate option as a menu entry in the compact view and as an icon in the tabbed view." type="bool" default="false">false</enabled>
        <api_url desc="URL for the API" type="string" default=""></api_url>
        <auth_key desc="Auth Key generated by your account" type="string" default=""></auth_key>
    </deepl>

    <sys_template_path desc="Path to a template tree with shared libraries etc to be used as source for chroot jails for child processes." type="path" relative="true" default="systemplate"></sys_template_path>
    <child_root_path desc="Path to the directory under which the chroot jails for the child processes will be created. Should be on the same file system as systemplate and lotemplate. Must be an empty directory." type="path" relative="true" default="jails"></child_root_path>
    <mount_jail_tree desc="Controls whether the systemplate and lotemplate contents are mounted or not, which is much faster than the default of linking/copying each file." type="bool" default="true">false</mount_jail_tree>
    <mount_namespaces desc="Use mount namespaces instead of coolmount." type="bool" default="true">true</mount_namespaces>

    <server_name desc="External hostname:port of the server running coolwsd. If empty, it's derived from the request (please set it if this doesn't work). May be specified when behind a reverse-proxy or when the hostname is not reachable directly." type="string" default="">cloud.domain.net:443</server_name>
    <file_server_root_path desc="Path to the directory that should be considered root for the file server. This should be the directory containing cool." type="path" relative="true" default="browser/../"></file_server_root_path>
    <hexify_embedded_urls desc="Enable to protect encoded URLs from getting decoded by intermediate hops. Particularly useful on Azure deployments" type="bool" default="false"></hexify_embedded_urls>
    <experimental_features desc="Enable/Disable experimental features" type="bool" default="true">true</experimental_features>

    <memproportion desc="The maximum percentage of system memory consumed by all of the Collabora Online Development Edition, after which we start cleaning up idle documents" type="double" default="80.0"></memproportion>
    <num_prespawn_children desc="Number of child processes to keep started in advance and waiting for new clients." type="uint" default="1">2</num_prespawn_children>
    <!-- <fetch_update_check desc="Every number of hours will fetch latest version data. Defaults to 10 hours." type="uint" default="10">10</fetch_update_check> -->
    <per_document desc="Document-specific settings, including LO Core settings.">
        <max_concurrency desc="The maximum number of threads to use while processing a document." type="uint" default="4">4</max_concurrency>
        <batch_priority desc="A (lower) priority for use by batch eg. convert-to processes to avoid starving interactive ones" type="uint" default="5">5</batch_priority>
        <document_signing_url desc="The endpoint URL of signing server, if empty the document signing is disabled" type="string" default=""></document_signing_url>
        <redlining_as_comments desc="If true show red-lines as comments" type="bool" default="false">false</redlining_as_comments>
        <pdf_resolution_dpi desc="The resolution, in DPI, used to render PDF documents as image. Memory consumption grows proportionally. Must be a positive value less than 385. Defaults to 96." type="uint" default="96">96</pdf_resolution_dpi>
        <idle_timeout_secs desc="The maximum number of seconds before unloading an idle document. Defaults to 1 hour." type="uint" default="3600">3600</idle_timeout_secs>
        <idlesave_duration_secs desc="The number of idle seconds after which document, if modified, should be saved. Disabled when 0. Defaults to 30 seconds." type="uint" default="30">10</idlesave_duration_secs>
        <autosave_duration_secs desc="The number of seconds after which document, if modified, should be saved. Disabled when 0. Defaults to 5 minutes." type="uint" default="300">120</autosave_duration_secs>
        <background_autosave desc="Allow auto-saves to occur in a forked background process where possible." type="bool" default="true">true</background_autosave>
        <background_manualsave desc="Allow manual save to occur in a forked background process where possible" type="bool" default="true">true</background_manualsave>
        <always_save_on_exit desc="On exiting the last editor, always perform the save, even if the document is not modified." type="bool" default="false">true</always_save_on_exit>
        <limit_virt_mem_mb desc="The maximum virtual memory allowed to each document process. 0 for unlimited." type="uint">0</limit_virt_mem_mb>
        <limit_stack_mem_kb desc="The maximum stack size allowed to each document process. 0 for unlimited." type="uint">20000</limit_stack_mem_kb>
        <limit_file_size_mb desc="The maximum file size allowed to each document process to write. 0 for unlimited." type="uint">0</limit_file_size_mb>
        <limit_num_open_files desc="The maximum number of files allowed to each document process to open. 0 for unlimited." type="uint">0</limit_num_open_files>
        <limit_load_secs desc="Maximum number of seconds to wait for a document load to succeed. 0 for unlimited." type="uint" default="100">100</limit_load_secs>
        <limit_store_failures desc="Maximum number of consecutive save-and-upload to storage failures when unloading the document. 0 for unlimited (not recommended)." type="uint" default="5">5</limit_store_failures>
        <limit_convert_secs desc="Maximum number of seconds to wait for a document conversion to succeed. 0 for unlimited." type="uint" default="100">100</limit_convert_secs>
        <min_time_between_saves_ms desc="Minimum number of milliseconds between saving the document on disk." type="uint" default="500">500</min_time_between_saves_ms>
        <min_time_between_uploads_ms desc="Minimum number of milliseconds between uploading the document to storage." type="uint" default="5000">5000</min_time_between_uploads_ms>
        <cleanup desc="Checks for resource consuming (bad) documents and kills associated kit process. A document is considered resource consuming (bad) if is in idle state for idle_time_secs period and memory usage passed limit_dirty_mem_mb or CPU usage passed limit_cpu_per" enable="true">
            <cleanup_interval_ms desc="Interval between two checks" type="uint" default="10000">10000</cleanup_interval_ms>
            <bad_behavior_period_secs desc="Minimum time period for a document to be in bad state before associated kit process is killed. If in this period the condition for bad document is not met once then this period is reset" type="uint" default="60">60</bad_behavior_period_secs>
            <idle_time_secs desc="Minimum idle time for a document to be candidate for bad state" type="uint" default="300">300</idle_time_secs>
            <limit_dirty_mem_mb desc="Minimum memory usage for a document to be candidate for bad state" type="uint" default="3072">3072</limit_dirty_mem_mb>
            <limit_cpu_per desc="Minimum CPU usage for a document to be candidate for bad state" type="uint" default="85">85</limit_cpu_per>
            <lost_kit_grace_period_secs desc="The minimum grace period for a lost kit process (not referenced by coolwsd) to resolve its lost status before it is terminated. To disable the cleanup of lost kits use value 0" default="120">120</lost_kit_grace_period_secs>
        </cleanup>
    </per_document>

    <per_view desc="View-specific settings.">
        <group_download_as desc="If set to true, groups download as icons into a dropdown for the notebookbar view." type="bool" default="true">true</group_download_as>
        <out_of_focus_timeout_secs desc="The maximum number of seconds before dimming and stopping updates when the browser tab is no longer in focus. Defaults to 120 seconds." type="uint" default="120">120</out_of_focus_timeout_secs>
        <idle_timeout_secs desc="The maximum number of seconds before dimming and stopping updates when the user is no longer active (even if the browser is in focus). Defaults to 15 minutes." type="uint" default="900">900</idle_timeout_secs>
    </per_view>

    <ver_suffix desc="Appended to etags to allow easy refresh of changed files during development" type="string" default=""></ver_suffix>

    <logging>
        <color type="bool">true</color>
        <!--
             Note to developers: When you do "make run", the logging.level will be set on the
             coolwsd command line, so if you want to change it for your testing, do it in
             Makefile.am, not here.
        -->
        <level type="string" desc="Can be 0-8 (with the lowest numbers being the least verbose), or none (turns off logging), fatal, critical, error, warning, notice, information, debug, trace" default="warning">trace</level>
        <level_startup type="string" desc="As for level - but for the initial startup phase which is most problematic, logging reverts to level configured above when startup is complete" default="trace">trace</level_startup>
        <most_verbose_level_settable_from_client type="string" desc="A loggingleveloverride message from the client can not set a more verbose log level than this" default="notice">notice</most_verbose_level_settable_from_client>
        <least_verbose_level_settable_from_client type="string" desc="A loggingleveloverride message from a client can not set a less verbose log level than this" default="fatal">fatal</least_verbose_level_settable_from_client>
        <protocol type="bool" desc="Enable minimal client-site JS protocol logging from the start">false</protocol>
        <!-- lokit_sal_log example: Log WebDAV-related messages, that is interesting for debugging Insert - Image operation: "+TIMESTAMP+INFO.ucb.ucp.webdav+WARN.ucb.ucp.webdav"
             See also: https://docs.libreoffice.org/sal/html/sal_log.html -->
        <lokit_sal_log type="string" desc="Fine tune log messages from LOKit. Default is to suppress log messages from LOKit." default="-INFO-WARN">-INFO-WARN</lokit_sal_log>
        <file enable="false">
            <!-- If you use other path than /var/log and you run coolwsd from systemd, make sure that you enable that path in coolwsd.service (ReadWritePaths). -->
            <property name="path" desc="Log file path.">/var/log/coolwsd.log</property>
            <property name="rotation" desc="Log file rotation strategy. See Poco FileChannel.">never</property>
            <property name="archive" desc="Append either timestamp or number to the archived log filename.">timestamp</property>
            <property name="compress" desc="Enable/disable log file compression.">true</property>
            <property name="purgeAge" desc="The maximum age of log files to preserve. See Poco FileChannel.">10 days</property>
            <property name="purgeCount" desc="The maximum number of log archives to preserve. Use 'none' to disable purging. See Poco FileChannel.">10</property>
            <property name="rotateOnOpen" desc="Enable/disable log file rotation on opening.">true</property>
            <property name="flush" desc="Enable/disable flushing after logging each line. May harm performance. Note that without flushing after each line, the log lines from the different processes will not appear in chronological order.">false</property>
        </file>
        <anonymize>
            <anonymize_user_data type="bool" desc="Enable to anonymize/obfuscate of user-data in logs. If default is true, it was forced at compile-time and cannot be disabled." default="false">false</anonymize_user_data>
            <anonymization_salt type="uint" desc="The salt used to anonymize/obfuscate user-data in logs. Use a secret 64-bit random number." default="82589933">82589933</anonymization_salt>
        </anonymize>
        <docstats type="bool" desc="Enable to see document handling information in logs." default="false">false</docstats>
        <userstats desc="Enable user stats. i.e: logs the details of a file and user" type="bool" default="false">false</userstats>
    </logging>

    <!--
         Note to developers: When you do "make run", the trace_event[@enable] will be set on the
         coolwsd command line, so if you want to change it for your testing, do it in Makefile.am,
         not here.
    -->
    <trace_event desc="The possibility to turn on generation of a Chrome Trace Event file" enable="false">
        <path desc="Output path for the Trace Event file, to which they will be written if turned on at run-time" type="string" default="/var/log/coolwsd.trace.json">/var/log/coolwsd.trace.json</path>
    </trace_event>

    <browser_logging desc="Logging in the browser console" default="false">false</browser_logging>

    <trace desc="Dump commands and notifications for replay. When 'snapshot' is true, the source file is copied to the path first." enable="false">
        <path desc="Output path to hold trace file and docs. Use '%' for timestamp to avoid overwriting. For example: /some/path/to/cooltrace-%.gz" compress="true" snapshot="false"></path>
        <filter>
            <message desc="Regex pattern of messages to exclude"></message>
        </filter>
        <outgoing>
            <record desc="Whether or not to record outgoing messages" default="false">false</record>
        </outgoing>
    </trace>

    <net desc="Network settings">
      <!-- On systems where localhost resolves to IPv6 [::1] address first, when net.proto is all and net.listen is loopback, coolwsd unexpectedly listens on [::1] only.
           You need to change net.proto to IPv4, if you want to use 127.0.0.1. -->
      <proto type="string" default="all" desc="Protocol to use IPv4, IPv6 or all for both">IPv6</proto>
      <listen type="string" default="any" desc="Listen address that coolwsd binds to. Can be 'any' or 'loopback'.">any</listen>
      <!-- this allows you to shift all of our URLs into a sub-path from
           https://my.com/browser/a123... to https://my.com/my/sub/path/browser/a123... -->
      <service_root type="path" default="" desc="Prefix all the pages, websockets, etc. with this path."></service_root>
      <post_allow desc="Allow/deny client IP address for POST(REST)." allow="true">
        <host desc="ULA of local network">fd01:.*</host>
        <host desc="Ditto, but as IPv4-mapped IPv6 addresses">::ffff:192\.168\.[0-9]{1,3}\.[0-9]{1,3}</host>
        <host desc="Ditto, but as IPv4-mapped IPv6 address">::ffff:127\.0\.0\.1</host>
        <host desc="The IPv6 loopback (localhost) address.">::1</host>
        <host desc="Ditto, but as IPv4-mapped IPv6 addresses">::ffff:172\.1[6789]\.[0-9]{1,3}\.[0-9]{1,3}</host>
        <host desc="Ditto, but as IPv4-mapped IPv6 addresses">::ffff:172\.2[0-9]\.[0-9]{1,3}\.[0-9]{1,3}</host>
        <host desc="Ditto, but as IPv4-mapped IPv6 addresses">::ffff:172\.3[01]\.[0-9]{1,3}\.[0-9]{1,3}</host>
        <host desc="Ditto, but as IPv4-mapped IPv6 addresses">::ffff:10\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}</host>
      </post_allow>
      <frame_ancestors desc="Specify who is allowed to embed the Collabora Online iframe (coolwsd and WOPI host are always allowed). Separate multiple hosts by space."></frame_ancestors>
      <connection_timeout_secs desc="Specifies the connection, send, recv timeout in seconds for connections initiated by coolwsd (such as WOPI connections)." type="int" default="30"></connection_timeout_secs>

      <!-- this setting radically changes how online works, it should not be used in a production environment -->
      <proxy_prefix type="bool" default="false" desc="Enable a ProxyPrefix to be passed int through which to redirect requests"></proxy_prefix>
    </net>

    <ssl desc="SSL settings">
        <!-- switches from https:// + wss:// to http:// + ws:// -->
        <enable type="bool" desc="Controls whether SSL encryption between coolwsd and the network is enabled (do not disable for production deployment). If default is false, must first be compiled with SSL support to enable." default="true">true</enable>
        <!-- SSL off-load can be done in a proxy, if so disable SSL, and enable termination below in production -->
        <termination desc="Connection via proxy where coolwsd acts as working via https, but actually uses http." type="bool" default="true">false</termination>
        <cert_file_path desc="Path to the cert file" relative="false">/etc/coolwsd/cert.pem</cert_file_path>
        <key_file_path desc="Path to the key file" relative="false">/etc/coolwsd/key.pem</key_file_path>
        <ca_file_path desc="Path to the ca file" relative="false">/etc/coolwsd/ca-chain.cert.pem</ca_file_path>
        <cipher_list desc="List of OpenSSL ciphers to accept" default="ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH"></cipher_list>
        <hpkp desc="Enable HTTP Public key pinning" enable="false" report_only="false">
            <max_age desc="HPKP's max-age directive - time in seconds browser should remember the pins" enable="true">1000</max_age>
            <report_uri desc="HPKP's report-uri directive - pin validation failure are reported at this URL" enable="false"></report_uri>
            <pins desc="Base64 encoded SPKI fingerprints of keys to be pinned">
            <pin></pin>
            </pins>
        </hpkp>
        <sts desc="Strict-Transport-Security settings, per rfc6797. Subdomains are always included.">
            <enabled desc="Whether or not Strict-Transport-Security is enabled. Enable only when ready for production. Cannot be disabled without resetting the browsers." type="bool" default="false">false</enabled>
            <max_age desc="Strict-Transport-Security max-age directive, in seconds. 0 is allowed; please see rfc6797 for details. Defaults to 1 year." type="int" default="31536000">31536000</max_age>
        </sts>
    </ssl>

    <security desc="Altering these defaults potentially opens you to significant risk">
      <seccomp desc="Should we use the seccomp system call filtering." type="bool" default="true">true</seccomp>
      <capabilities desc="Should we require capabilities to isolate processes into chroot jails" type="bool" default="true">true</capabilities>
      <jwt_expiry_secs desc="Time in seconds before the Admin Console's JWT token expires" type="int" default="1800">1800</jwt_expiry_secs>
      <enable_macros_execution desc="Specifies whether the macro execution is enabled in general. This will enable Basic and Python scripts to execute both installed and from documents. If it is set to false, the macro_security_level is ignored. If it is set to true, the mentioned entry specified the level of macro security." type="bool" default="false">false</enable_macros_execution>
      <macro_security_level desc="Level of Macro security. 1 (Medium) Confirmation required before executing macros from untrusted sources. 0 (Low, not recommended) All macros will be executed without confirmation." type="int" default="1">1</macro_security_level>
      <enable_metrics_unauthenticated desc="When enabled, the /cool/getMetrics endpoint will not require authentication." type="bool" default="false">false</enable_metrics_unauthenticated>
    </security>

    <certificates>
      <database_path type="string" desc="Path to the NSS certificates that are used for signing documents" default=""></database_path>
    </certificates>

    <watermark>
      <opacity desc="Opacity of on-screen watermark from 0.0 to 1.0" type="double" default="0.2"></opacity>
      <text desc="Watermark text to be displayed on the document if entered" type="string"></text>
    </watermark>


    <user_interface>
      <mode type="string" desc="Controls the user interface style. The 'default' means: Take the value from ui_defaults, or decide for one of compact or tabbed (default|compact|tabbed)" default="default">default</mode>
      <use_integration_theme desc="Use theme from the integrator" type="bool" default="true">true</use_integration_theme>
    </user_interface>

    <storage desc="Backend storage">
        <filesystem allow="false" />
        <wopi desc="Allow/deny wopi storage." allow="true">
            <max_file_size desc="Maximum document size in bytes to load. 0 for unlimited." type="uint">0</max_file_size>
            <locking desc="Locking settings">
                <refresh desc="How frequently we should re-acquire a lock with the storage server, in seconds (default 15 mins) or 0 for no refresh" type="int" default="900">900</refresh>
            </locking>

            <alias_groups desc="default mode is 'first' it allows only the first host when groups are not defined. set mode to 'groups' and define group to allow multiple host and its aliases" mode="first">
            <!-- If you need to use multiple wopi hosts, please change the mode to "groups" and
                    add the hosts below.  If one host is accessible under multiple ip addresses
                    or names, add them as aliases. -->
            <!--<group>
                    <host desc="hostname to allow or deny." allow="true">scheme://hostname:port</host>
                    <alias desc="regex pattern of aliasname">scheme://aliasname1:port</alias>
                    <alias desc="regex pattern of aliasname">scheme://aliasname2:port</alias>
                    
            </group>-->
            <!-- More "group"s possible here -->
            </alias_groups>

        </wopi>
        <ssl desc="SSL settings">
            <as_scheme type="bool" default="true" desc="When set we exclusively use the WOPI URI's scheme to enable SSL for storage">true</as_scheme>
            <enable type="bool" desc="If as_scheme is false or not set, this can be set to force SSL encryption between storage and coolwsd. When empty this defaults to following the ssl.enable setting"></enable>
            <cert_file_path desc="Path to the cert file" relative="false"></cert_file_path>
            <key_file_path desc="Path to the key file" relative="false"></key_file_path>
            <ca_file_path desc="Path to the ca file. If this is not empty, then SSL verification will be strict, otherwise cert of storage (WOPI-like host) will not be verified." relative="false"></ca_file_path>
            <cipher_list desc="List of OpenSSL ciphers to accept. If empty the defaults are used. These can be overridden only if absolutely needed."></cipher_list>
        </ssl>
    </storage>

    <tile_cache_persistent desc="Should the tiles persist between two editing sessions of the given document?" type="bool" default="true">true</tile_cache_persistent>

    <admin_console desc="Web admin console settings.">
        <enable desc="Enable the admin console functionality" type="bool" default="true">true</enable>
        <enable_pam desc="Enable admin user authentication with PAM" type="bool" default="false">false</enable_pam>
        <username desc="The username of the admin console. Ignored if PAM is enabled.">xxxxxxx</username>
        <password desc="The password of the admin console. Deprecated on most platforms. Instead, use PAM or coolconfig to set up a secure password.">xxxxxx</password>
    </admin_console>

    <monitors desc="Addresses of servers we connect to on start for monitoring">
    </monitors>

    <quarantine_files desc="Files are stored here to be examined later in cases of crashes or similar situation." default="false" enable="false">
        <limit_dir_size_mb desc="Maximum directory size. On exceeding the specified limit, older files will be deleted." default="250" type="uint"></limit_dir_size_mb>
        <max_versions_to_maintain desc="How many versions of the same file to keep." default="2" type="uint"></max_versions_to_maintain>
        <path desc="Path to directory under which quarantined files will be stored" type="path" relative="true" default="quarantine"></path>
        <expiry_min desc="Time in mins after quarantined files will be deleted." type="int" default="30"></expiry_min>
    </quarantine_files>

    <remote_config>
        <remote_url desc="remote server to which you will send resquest to get remote config in response" type="string" default=""></remote_url>
    </remote_config>

    <remote_font_config>
        <url desc="URL of optional JSON file that lists fonts to be included in Online" type="string" default=""></url>
    </remote_font_config>

    <home_mode>
        <enable desc="Enable more configuration options for home users" type="bool" default="false">false</enable>
    </home_mode>

    <fonts_missing>
        <handling desc="How to handle fonts mising in a document: 'report', 'log', 'both', or 'ignore'" type="string" default="log">log</handling>
    </fonts_missing>

    <indirection_endpoint>
        <url desc="URL endpoint to server which servers routeToken in json format" default=""></url>
    </indirection_endpoint>

    

    

    <zotero dec="Zotero plugin configuration. For more details about Zotero visit https://www.zotero.org/">
        <enable dec="Enable Zotero plugin." type="bool" default="true">true</enable>
    </zotero>

</config>

Logs

Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659723 -0700 [ accept_poll ] TRC  #14: Accepted socket #23, creating socket object.| net/Socket.cpp:1217
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659792 -0700 [ accept_poll ] DBG  #23: Created socket. Thread affinity set to 0x7ec059dfd6c0, Socket[#23, IPv6 @ :0]| net/Socket.hpp:474
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659804 -0700 [ accept_poll ] TRC  #23: StreamSocket ctor| net/Socket.hpp:1075
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659807 -0700 [ accept_poll ] TRC  #23: SslStreamSocket ctor #23| net/SslSocket.hpp:45
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659831 -0700 [ accept_poll ] TRC  #23: Setting SSL into accept state| net/SslSocket.hpp:84
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659834 -0700 [ accept_poll ] TRC  #23: setHandler| net/Socket.hpp:1343
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659837 -0700 [ accept_poll ] TRC  #23: Connected to ClientRequestDispatcher| wsd/ClientRequestDispatcher.cpp:615
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659840 -0700 [ accept_poll ] TRC  #14: Accepted socket #23 has family 10, StreamSocket[#23, HTTP, IPv6 @ [fd01::1:172:20:20:6]:21121]| net/Socket.cpp:1257
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659844 -0700 [ accept_poll ] TRC  Inserting socket #23, address [fd01::1:172:20:20:6], into websrv_poll| net/Socket.hpp:844
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300890 2025-03-20 22:00:36.659847 -0700 [ accept_poll ] TRC  #23: Resetting thread affinity while in transit (was 0x7ec059dfd6c0)| net/Socket.hpp:391
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.659929 -0700 [ websrv_poll ] TRC  #23: Thread affinity set to 0x7ec0595fc6c0 (was 0)| net/Socket.hpp:380
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.659961 -0700 [ websrv_poll ] TRC  PollSocket container size has changed from 0 to 1| net/Socket.cpp:610
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.663386 -0700 [ websrv_poll ] DBG  #23: SSL error (handshake): WANT_READ (2), rc: -1, errno: 11 (EAGAIN: Resource temporarily unavailable): BIO error: 0: error:00000000:lib(0)::reason(0):| net/SslSocket.hpp:387
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.663421 -0700 [ websrv_poll ] TRC  #23: WANT_READ with no(0) pending data to read| net/SslSocket.hpp:415
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664101 -0700 [ websrv_poll ] TRC  #23: SSL handshake completed successfully| net/SslSocket.hpp:273
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664115 -0700 [ websrv_poll ] DBG  #23: SSL error (read): WANT_READ (2), rc: -1, errno: 11 (EAGAIN: Resource temporarily unavailable): BIO error: 0: error:00000000:lib(0)::reason(0):| net/SslSocket.hpp:387
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664126 -0700 [ websrv_poll ] TRC  #23: WANT_READ with no(0) pending data to read| net/SslSocket.hpp:415
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664141 -0700 [ websrv_poll ] DBG  #23: SSL error (read): WANT_READ (2), rc: -1, errno: 11 (EAGAIN: Resource temporarily unavailable): BIO error: 0: error:00000000:lib(0)::reason(0):| net/SslSocket.hpp:387
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664145 -0700 [ websrv_poll ] TRC  #23: WANT_READ with (0) pending data to read| net/SslSocket.hpp:415
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664235 -0700 [ websrv_poll ] INF  #23: parseHeader: Client HTTP Request: POST, uri: [/browser/ded56d8ff7/cool.html?WOPISrc=https%3A%2F%2Fcloud.domain.net%2Findex.php%2Fapps%2Frichdocuments%2Fwopi%2Ffiles%2F108651_oczo9l6g28gh&lang=en&closebutton=1&revisionhistory=1] HTTP/1.0, sz[header 1152, content 4244], offset 1152, chunked false, X-Forwarded-For: fd01::a:10:10:0:2 / Connection: close / Content-Length: 4244 / user-agent: Mozilla/5.0 (X11; Linux x86_64; rv:136.0) Gecko/20100101 Firefox/136.0 / accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 / accept-language: en-US,en;q=0.5 / accept-encoding: gzip, deflate, br, zstd / content-type: application/x-www-form-urlencoded / origin: null / dnt: 1 / sec-gpc: 1 / upgrade-insecure-requests: 1 / sec-fetch-dest: iframe / sec-fetch-mode: navigate / sec-fetch-site: same-origin / sec-fetch-user: ?1 / alt-used: cloud.domain.net / priority: u=4 / cookie: __Host-nc_sameSiteCookielax=true; __Host-nc_sameSiteCookiestrict=true; nc_username=admin; nc_token=xxxx; nc_session_id=xxxx; oc_sessionPassphrase=xxx;| net/Socket.cpp:1557
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664248 -0700 [ websrv_poll ] DBG  #23: Handling request: /browser/ded56d8ff7/cool.html?WOPISrc=https%3A%2F%2Fcloud.domain.net%2Findex.php%2Fapps%2Frichdocuments%2Fwopi%2Ffiles%2F108651_oczo9l6g28gh&lang=en&closebutton=1&revisionhistory=1, closeConnection true| wsd/ClientRequestDispatcher.cpp:700
Mar 20 22:00:36 cloud coolwsd[300874]: [380B blob data]
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664325 -0700 [ websrv_poll ] TRC  #23: Async shutdown requested.| net/Socket.hpp:1119
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664329 -0700 [ websrv_poll ] TRC  #23: Ignore further input on socket.| net/Socket.hpp:412
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664334 -0700 [ websrv_poll ] TRC  #23: Shutdown Signaled. Close Connection.| net/Socket.hpp:1562
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664337 -0700 [ websrv_poll ] DBG  #23: SslStreamSocket::shutdownConnection() #23| net/SslSocket.hpp:136
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664344 -0700 [ websrv_poll ] TRC  #23: Socket shutdown RDWR. StreamSocket[#23, HTTP, IPv6 @ [fd01::1:172:20:20:6]:21121]| net/Socket.hpp:227
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664355 -0700 [ websrv_poll ] TRC  #23: Closed. Firing onDisconnect.| net/Socket.hpp:1590
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664358 -0700 [ websrv_poll ] TRC  Executing SocketDisposition of #23: Type::CLOSED| net/Socket.cpp:980
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664361 -0700 [ websrv_poll ] TRC  #23: SslStreamSocket dtor #23| net/SslSocket.hpp:105
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664370 -0700 [ websrv_poll ] TRC  #23: StreamSocket dtor called with pending write: 0, read: 0| net/Socket.hpp:1082
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664373 -0700 [ websrv_poll ] TRC  #23: Socket dtor| net/Socket.hpp:161
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664381 -0700 [ websrv_poll ] DBG  #23: Closed socket Socket[#23, IPv6 @ fd01::1:172:20:20:6:21121]| net/Socket.hpp:171
Mar 20 22:00:36 cloud coolwsd[300874]: wsd-300874-300891 2025-03-20 22:00:36.664384 -0700 [ websrv_poll ] TRC  Scanning to removing 1 defunct sockets from 1 sockets| net/Socket.cpp:688

[tunloop]

Looking at the console during document opening:

/browser/ded56d8ff7/cool.html?WOPISrc=https%3A%2F%2Fcloud.domain.net%2Findex.php%2Fapps%2Frichdocuments%2Fwopi%2Ffiles%2F115608_oczo9l6g28gh&lang=en&closebutton=1&revisionhistory=1 [HTTP/3 400  4ms]

Not sure why I'm getting a 400... Don't think its my proxy (not a 5XX)

Just tried in some other browsers just to rule it out...
konqueror used http2.0 and got 200 code but the document still didn't load.
chromium used http3.0 and got 400 code, and the document didn't load.

Just to test this theory out, I disabled HTTP3/QUIC in my NGINX reverse proxy, and the document loading works again.

I'll update the title to reflect this as a HTTP3 support issue.