Studio: Improve context for errors that bubble up from wordpress-server-child

apps/cli/lib/wordpress-server-manager.ts

@@ -390,7 +390,11 @@ export async function sendMessage(
 		processEventHandler = ( event ) => {
 			if ( event.process.name === processName && event.event === 'exit' ) {
 				exitRejectTimeoutId = setTimeout( () => {
-					reject( new Error( 'WordPress server process exited unexpectedly' ) );
+					let errorMessage = 'WordPress server process exited unexpectedly';
+					if ( event.stderrTail?.trim() ) {
+						errorMessage += `\n${ event.stderrTail.trimEnd() }`;
+					}
+					reject( new Error( errorMessage ) );
 				}, CHILD_EXIT_ERROR_GRACE_MS );
 			}
 		};

apps/studio/src/hooks/use-site-details.tsx

@@ -13,7 +13,7 @@ import {
 } from 'react';
 import { useContentTabs } from 'src/hooks/use-content-tabs';
 import { useIpcListener } from 'src/hooks/use-ipc-listener';
-import { simplifyErrorForDisplay } from 'src/lib/error-formatting';
+import { simplifyErrorForDisplay, simplifyErrorToFirstSentence } from 'src/lib/error-formatting';
 import { getIpcApi } from 'src/lib/get-ipc-api';
 import type { Blueprint } from 'src/stores/wpcom-api';
 
@@ -271,7 +271,7 @@ export function SiteDetailsProvider( { children }: SiteDetailsProviderProps ) {
 					message = __(
 						'The selected Blueprint failed to execute properly. This could be due to invalid PHP code, missing plugins, or other issues in the Blueprint file. Please check your Blueprint file and try again.'
 					);
-					errorToShow = undefined;
+					errorToShow = simplifyErrorToFirstSentence( error );
 				} else {
 					title = __( 'Failed to create site' );
 					message = __(
@@ -285,7 +285,7 @@ export function SiteDetailsProvider( { children }: SiteDetailsProviderProps ) {
 					title,
 					message,
 					error: errorToShow,
-					showOpenLogs: ! isBlueprintError || ! hasBlueprint,
+					showOpenLogs: true,
 				} );
 
 				// Remove the temporary site immediately, but with a minor delay to ensure state updates properly

apps/studio/src/ipc-handlers.ts

@@ -90,7 +90,10 @@ import {
 	trustRootCA,
 } from 'src/lib/certificate-manager';
 import { download } from 'src/lib/download';
-import { simplifyErrorForDisplay } from 'src/lib/error-formatting';
+import {
+	extractErrorFromProcessManagerLogs,
+	simplifyErrorForDisplay,
+} from 'src/lib/error-formatting';
 import { buildFeatureFlags } from 'src/lib/feature-flags';
 import { getImageData } from 'src/lib/get-image-data';
 import { getUserLocaleWithFallback } from 'src/lib/locale-node';
@@ -715,8 +718,10 @@ function readWordPressDebugLog( sitePath: string ): string[] | undefined {
 
 function readProcessManagerLogs( siteId: string ): { stdout?: string[]; stderr?: string[] } {
 	const logsDir = nodePath.join( PROCESS_MANAGER_HOME, 'logs' );
-	const stdoutPath = nodePath.join( logsDir, `studio-site-${ siteId }-out.log` );
-	const stderrPath = nodePath.join( logsDir, `studio-site-${ siteId }-error.log` );
+	const dateTag = new Date().toISOString().slice( 0, 10 ).replace( /-/g, '' );
+	const prefix = `studio-site-${ siteId }`;
+	const stdoutPath = nodePath.join( logsDir, `${ prefix }-out-${ dateTag }.log` );
+	const stderrPath = nodePath.join( logsDir, `${ prefix }-error-${ dateTag }.log` );
 
 	return {
 		stdout: readLastLines( stdoutPath, DEBUG_LOG_MAX_LINES ),
@@ -873,6 +878,14 @@ export async function createSite(
 			contexts,
 		} );
 
+		// If the error message is generic, try to surface a more useful message from
+		// the process manager logs. The detailed error is often captured in stdout
+		// (e.g. blueprint execution errors logged by playground-cli).
+		const logErrorMessage = extractErrorFromProcessManagerLogs( processManagerLogs );
+		if ( logErrorMessage ) {
+			throw new Error( logErrorMessage );
+		}
+
 		throw error;
 	} finally {
 		if ( bundleTempDir ) {

apps/studio/src/lib/error-formatting.ts

@@ -15,3 +15,37 @@ export function simplifyErrorForDisplay( error: unknown ): Error {
 	}
 	return new Error( String( error ) );
 }
+
+/**
+ * Like `simplifyErrorForDisplay`, but also truncates to the first sentence.
+ * Useful when the first line is a long, detailed error message and the dialog
+ * should stay concise (e.g. blueprint errors). Full details are available via logs.
+ */
+export function simplifyErrorToFirstSentence( error: unknown ): Error {
+	const simplified = simplifyErrorForDisplay( error );
+	const firstSentence = simplified.message.match( /^[^.]+\./ );
+	return firstSentence ? new Error( firstSentence[ 0 ] ) : simplified;
+}
+
+/**
+ * Extract a user-facing error message from process manager logs. The child process often logs
+ * detailed error information to stdout (via playground-cli) before exiting. This scans log
+ * lines for "Error:" prefixed entries which typically contain the root cause.
+ */
+export function extractErrorFromProcessManagerLogs( logs: {
+	stdout?: string[];
+	stderr?: string[];
+} ): string | undefined {
+	const lines = [ ...( logs.stdout ?? [] ), ...( logs.stderr ?? [] ) ];
+
+	for ( let i = lines.length - 1; i >= 0; i-- ) {
+		// Log lines are timestamped: "2026-05-15T08:38:04.859Z Error: ..."
+		// Strip the timestamp prefix to get the raw message.
+		const line = lines[ i ].replace( /^\d{4}-\d{2}-\d{2}T[\d:.]+Z\s*/, '' ).trim();
+		if ( line.startsWith( 'Error:' ) || line.startsWith( 'Error when' ) ) {
+			return line;
+		}
+	}
+
+	return undefined;
+}