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
- Capture failing tx logs (solana logs, explorer). Note exact error code.
- Decode instruction + accounts from tx; compare with expected order and flags.
- 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.
- For discriminator errors:
- Ensure correct account type created; check 8-byte discriminator.
- Rebuild + redeploy to clear stale data; avoid reusing addresses.
- For serialization/realloc issues:
- Ensure data length matches struct size; adjust rent or realloc correctly.
- CPI issues:
- Verify CPI account metas and signer seeds; inspect callee IDL.
- 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.
