fix(wallet): guard undefined connector on reconnect to stop refresh crash by tenderdeve · Pull Request #7772 · cowprotocol/cowswap

tenderdeve · 2026-06-30T13:43:16Z

Summary

On refresh, a connected wallet (repro: Rabby on Polygon) disconnects and the console throws Cannot read properties of undefined (reading 'id').

The throw comes from @reown/appkit-adapter-wagmi's watchAccount onChange handler, which reads accountData.connector.id unguarded — even though the very next operand already uses prevAccountData.connector?.id:

const hasConnectorChanged = accountData.connector.id !== prevAccountData.connector?.id;

During reconnection rehydration, wagmi can briefly report status: 'connected' before the connector object is attached (the window is wider with a custom injected connector + EIP-6963 isolation and a non-mainnet chain). accountData.connector is then undefined, so .id throws. Because the throw happens inside the connected handler, reconnection never finalizes and the wallet ends up disconnected — both reported symptoms from one line.

Extended the existing patches/@reown__appkit-adapter-wagmi@1.8.19.patch to read accountData.connector?.id, matching the optional chaining already used on the previous value.

To Test

Connect a wallet (e.g. Rabby) on a non-mainnet chain like Polygon.

Refresh the page — no reading 'id' error in the console.
The wallet stays connected across the refresh instead of dropping.

Background

The unguarded .id is upstream library code, so the fix is a dependency patch rather than an app change. I don't have an on-device Rabby/Polygon setup to reproduce the exact rehydration timing, so this targets the single unguarded dereference the stack points to; the asymmetric optional chaining on the same line is a clear upstream oversight.

Summary by CodeRabbit

Bug Fixes
- Improved account change detection so wallet connection updates are handled more reliably.
- Fixed native balance display/return values by ensuring a readable balance is always derived when needed.
- Updated balance caching to use the same consistent formatted value shown to users.

vercel · 2026-06-30T13:43:22Z

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coderabbitai · 2026-06-30T13:43:29Z

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Walkthrough

Patches the @reown/appkit-adapter-wagmi@1.8.19 package to guard connector-change detection with optional chaining and a presence check on accountData.connector, and adds a fallback for computing native balance formatted values via formatUnits when balance.formatted is unavailable.

Changes

Wagmi adapter patch update

Layer / File(s)	Summary
Connector-change detection guard `patches/@reown__appkit-adapter-wagmi@1.8.19.patch`	Compares connector IDs with optional chaining and only evaluates the connector-change condition when `accountData.connector` exists, preventing undefined property reads during account updates.
Native balance formatted fallback `patches/@reown__appkit-adapter-wagmi@1.8.19.patch`	Derives `formatted` from `balance.formatted` or via `formatUnits(balance.value, balance.decimals)`, used for both the cache update and resolved return payload.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

cowprotocol/cowswap#7509: Fixes the same transient accountData.connector undefined issue during connected-state hydration in the wagmi adapter.

Suggested reviewers: elena-zh, limitofzero, kernelwhisperer

Poem

A hop, a patch, a guarded chain,
No more errors to explain,
Balances formatted, safe and sound,
Connectors checked before they're found,
This bunny thumps in pure delight— 🐇
Refresh the page, connection's tight!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The native balance formatting change is unrelated to the refresh crash fix and appears out of scope.	Remove the balance formatting tweak or split it into a separate PR unless it is required for `#7769`.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the refresh-time connector guard fix.
Description check	✅ Passed	The description follows the template with Summary, To Test, and Background sections and links the issue.
Linked Issues check	✅ Passed	The connector guard and gating address the refresh crash and disconnect reported in `#7769`.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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github-actions · 2026-06-30T13:46:07Z

Cloudflare Pages preview mirror

Preview branch URL: https://github.com/cowprotocol/cowswap/tree/cf-preview/pr-7772
Mirror PR: #7773
Cloudflare Pages preview links will be posted on the mirror PR by the Cloudflare Pages GitHub integration once builds complete.

Source fork branch: tenderdeve/cowswap:fix/7769-wallet-refresh-id-crash
Approval target SHA: 3864536caaf0
Last mirrored SHA: 3f548fcbd2de
Last comment update: @Danziger at 2026-07-10T10:23:19.243Z

Sync Cloudflare preview to approval target commit

elena-zh

Hey @tenderdeve , thanks, but not fixed.

tenderdeve · 2026-07-01T09:02:26Z

@elena-zh updated in 8bdd9b9 — the previous connector?.id guard only fixed the comparison; the crash then moved into handleAccountChanged, which calls connector.getProvider() (the new Cannot read properties of undefined (reading 'getProvider') in your screenshot). On refresh wagmi briefly reports status connected before the connector attaches. Now the connected account is only finalized once accountData.connector is present; wagmi re-fires onChange when the connector attaches, so nothing is lost and the wallet stays connected.

elena-zh

Looks good now, thanks

elena-zh · 2026-07-01T13:05:24Z

@tenderdeve could you please rebase the PR to point to develop instead of main?

elena-zh

See my comment above

tenderdeve · 2026-07-01T13:21:00Z

See my comment above

@elena-zh fixed, now PR pointed to develop

vercel · 2026-07-01T13:28:14Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
swap-dev	Ready	Preview	Jul 1, 2026 1:31pm

elena-zh

Thanks!

…rash @reown/appkit-adapter-wagmi reads `accountData.connector.id` unguarded in the `watchAccount` onChange handler, while the very next operand already uses `prevAccountData.connector?.id`. During reconnection rehydration on page refresh (e.g. Rabby on Polygon) wagmi can briefly report status 'connected' before the connector object is attached, so `.id` throws 'Cannot read properties of undefined (reading id)'. The throw aborts the connected handler, so reconnection never finalizes and the wallet ends up disconnected. Patch the dependency to read `accountData.connector?.id`, matching the existing optional chaining on the prev value.

The connector?.id guard alone only fixed the comparison in the watchAccount onChange handler; the crash then moved into handleAccountChanged, which calls connector.getProvider() and reads connector.id unguarded. On page refresh (e.g. Rabby on Polygon) wagmi can report status 'connected' before the connector object is attached, so getProvider() throws "Cannot read properties of undefined (reading 'getProvider')" and reconnection never finalizes, leaving the wallet disconnected. Only finalize the connected account when accountData.connector is present. The connector-less 'connected' state is a transient rehydration step; wagmi fires onChange again once the connector attaches (which registers as a connector change), so no event is lost.

tenderdeve · 2026-07-02T06:12:41Z

Rebased cleanly onto develop — the branch had merged main, which pulled in the unrelated zeroApproval/USDT change (#7775) that isn't in develop yet, so it was showing up in this PR's diff. Dropped the merge commits; the diff is now just the reown adapter patch + its pnpm-lock hash. @Themoor1 that stray shouldZeroApprove.ts file is gone now. @elena-zh no change to the actual fix you approved.

elena-zh added the trigger-preview Add to a fork PR to trigger CF-pages preview. See https://github.com/cowprotocol/cowswap/pull/7615 label Jun 30, 2026

github-actions Bot mentioned this pull request Jun 30, 2026

preview: mirror fork PR #7772 #7773

Closed

github-actions Bot removed the trigger-preview Add to a fork PR to trigger CF-pages preview. See https://github.com/cowprotocol/cowswap/pull/7615 label Jun 30, 2026

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elena-zh requested changes Jun 30, 2026

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elena-zh approved these changes Jul 1, 2026

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elena-zh requested review from elena-zh and limitofzero July 1, 2026 13:05

elena-zh requested changes Jul 1, 2026

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tenderdeve changed the base branch from main to develop July 1, 2026 13:20

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tenderdeve added 2 commits July 2, 2026 11:41

tenderdeve force-pushed the fix/7769-wallet-refresh-id-crash branch from 6f76a2a to 02249cf Compare July 2, 2026 06:12

cowprotocol deleted a comment Jul 2, 2026

fairlighteth assigned tenderdeve Jul 3, 2026

limitofzero approved these changes Jul 9, 2026

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Merge branch 'develop' into fix/7769-wallet-refresh-id-crash

3864536

Danziger enabled auto-merge (squash) July 10, 2026 10:25

Danziger merged commit 042991a into cowprotocol:develop Jul 10, 2026
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fix(wallet): guard undefined connector on reconnect to stop refresh crash - #7772

fix(wallet): guard undefined connector on reconnect to stop refresh crash#7772
Danziger merged 3 commits into
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tenderdeve:fix/7769-wallet-refresh-id-crash

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