Phantom iOS deeplink signAndSendTransaction errorCode=-32603

[HuberyQing]

Summary

Hi Phantom Team,

I am developing a third-party iOS app and trying to implement SOL transfer using the signAndSendTransaction deeplink flow.

However, when I build the transaction locally (in base64 format) and invoke Phantom via deeplink, I consistently receive the following callback:

arduino
wallet-demo://phantom-callback?errorCode=-32603&errorMessage=Unexpected+error
✅ My setup:
Network: mainnet-beta

Wallet address:

Transfer amount: 0.0001 SOL

Destination address:

Transaction is serialized using SolanaTransactionManager (compatible with Solana.Swift format)

Base64-encoded transaction:
(truncated) AQABA+9PlUemkgy9+4tU3Vb8uQfb4w7GBTjW2v1mhxemLcwZ...

deeplink URL length: 970 chars

🔍 What I’ve verified:
✅ Transaction is correctly constructed and serialized (can decode and inspect base58)

✅ feePayer, recentBlockhash, and from are all set properly

✅ Phantom is launched and user can interact, but signs fail

✅ Using mainnet-beta RPC endpoint: https://api.mainnet-beta.solana.com

✅ dapp_encryption_public_key and nonce are generated with TweetNacl

✅ I’ve tried reducing URL length and simplifying transaction, no luck

❓ Questions:
Is there a limit on transaction size or URL length for Phantom deeplink handling on iOS?

Does signAndSendTransaction only support transactions constructed in a certain structure (e.g., with specific field order or default empty signatures)?

Are there any restrictions on encoding or encryption used for the deeplink payload?

If needed, I can provide the full transaction payload and logs for debugging.
Any help would be greatly appreciated!

Thanks,

Example

No response

Steps to Reproduce

In a third-party iOS app, manually construct a Solana native transfer transaction without using Solana.Swift:

from:

to:

amount: 0.0001 SOL (i.e. 100,000 lamports)

recentBlockhash: obtained via RPC endpoint https://api.mainnet-beta.solana.com

feePayer: same as from

Build the unsigned transaction, serialize it to base64 format. Example:

AQABA+9PlUemkgy9+4tU3Vb8uQfb4w7GBTjW2v1mhxemLcwZ8m98N7rBBOzsDy/11RkGRSpTqeEeOz8OHCFwc5NZJ2UAAAA...
Byte length: 150

Base58 length: 204

Encrypt the transaction using a custom encryption module based on TweetNaCl, then generate the Phantom deeplink URL as follows:

bash
复制
编辑
https://phantom.app/ul/v1/signAndSendTransaction?
dapp_encryption_public_key=...
&nonce=...
&redirect_link=wallet-demo%3A%2F%2Fphantom-callback
&transaction=... // base64 encoded transaction
Open the deeplink via UIApplication.shared.open(URL).

Phantom wallet successfully opens and displays the transaction confirmation screen.

After user confirms the transaction, Phantom returns the callback URL:

arduino

wallet-demo://phantom-callback?errorCode=-32603&errorMessage=Unexpected+error
Additional Information
Phantom environment: latest iOS app version (mainnet network)

Network: Mainnet Beta

Transaction is unsigned; signing is delegated to Phantom

Encryption uses TweetNaCl with correct base58 public key, random nonce, and properly encoded redirect link

Phantom deeplink URL length is about 970 characters

The transaction is a standard SOL transfer with no additional instructions

Phantom Version

No response

Is there an existing discussion for this?

• I have searched the existing discussions

[Th3Ya0vi]

Hey @HuberyQing! We have announced changes to deeplink and signAndSendTransaction here https://github.com/orgs/phantom/discussions/449
If you're open to it, feel free to share your app logs or the full base64 transaction and encryption payload I can dig deeper.

Also, while there’s no hard limit on deeplink URL length, iOS may impose practical limits around 2,000 characters, so keeping it under ~1,500 is generally safe.