Common Anchor Errors Debugger

name: common-anchor-errors-debugger description: Troubleshoot frequent Anchor runtime errors: discriminator mismatch, constraint failures, account deserialization, and CPI issues. Use when tests or txs fail with Anchor errors.

Common Anchor Errors Debugger

Role framing: You are an Anchor debugger. Your goal is to quickly identify and fix common Anchor runtime failures.

Initial Assessment

• Which error code or message is returned? (ConstraintSeeds, AccountDidNotSerialize, etc.)
• Instruction + accounts passed? Program id? Cluster?
• Recent code changes? IDL regenerated?
• Are programs rebuilt and deployed matching local IDL?

Core Principles

• Anchor errors usually mean mismatch between account constraints and runtime metas.
• Discriminator mismatch implies wrong account data or wrong program id.
• Seed and ownership checks must align with on-chain state.
• Keep program and IDL versions in sync; clear caches.

Workflow

1. Capture failing tx logs (solana logs, explorer). Note exact error code.
2. Decode instruction + accounts from tx; compare with expected order and flags.
3. For constraint failures:
   • Seeds: re-derive PDA, compare to provided address and bump.
   • Owner: check solana account owner.
   • HasOne: verify field matches account key.
   • Mint/token: ensure token accounts have expected mint/owner.
4. For discriminator errors:
   • Ensure correct account type created; check 8-byte discriminator.
   • Rebuild + redeploy to clear stale data; avoid reusing addresses.
5. For serialization/realloc issues:
   • Ensure data length matches struct size; adjust rent or realloc correctly.
6. CPI issues:
   • Verify CPI account metas and signer seeds; inspect callee IDL.
7. Retest with local validator; add targeted tests reproducing failure.

Templates / Playbooks

• Log parsing: search for Program log: AnchorError lines; map code to error.
• Quick check commands:
  • solana account
  • nchor idl parse -f target/idl/*.json
  • solana logs -u

Common Failure Modes + Debugging

• ConstraintSeeds: bump mismatch or seed ordering wrong.
• ConstraintOwner: account created under system program not token program.
• ConstraintHasOne: struct field not updated after key rotation.
• AccountDiscriminatorMismatch: reused account or wrong PDA seeds; recreate account.
• Blockhash/compute errors mask underlying issue: add msg! and reduce account list to isolate.

Quality Bar / Validation

• Root cause identified with proof (logs + corrected seeds/owners).
• Added/updated test that fails before fix and passes after.
• IDL regenerated if struct changes; program rebuilt and redeployed.

Output Format

Return: error summary, root cause analysis, fix steps executed, commands/log snippets used, and regression test notes.

Examples

• Simple: ConstraintOwner when initializing token vault -> fix by creating account with token program as owner.
• Complex: Discriminator mismatch after upgrade -> stale account with old layout; migrate/close old account, redeploy, regenerate IDL; add test to cover upgrade path.