Append rows to my Google Sheets — until a policy check silently blocks every write
From early October 2026, the AI users found every write to Google Sheets failing in a pre-execution 'Blocking Policy Check' (PERMISSION_DENIED) while reads still worked, breaking Tasks-mode workflows that appended rows to Sheets and updated Docs changelogs. Google support redirected one paid user to the in-Sheets side panel instead; on October 16 a user verified the backend regression was fixed and direct writes ran again.
This one went wrong. Read what happened so you don’t hit the same problem.
How it works
- Users run Spark Tasks that append rows to Sheets and update Docs changelogs
- In early October the sheets_agent tool starts aborting on a blocking policy check before any write
- Reads keep working and manual edits work, even on anyone-can-edit files
- Support suggests using the Sheets side panel instead
- Oct 16 verification shows direct writes executing again
Why it’s worth knowing
The agent could read every spreadsheet but was stopped before writing by a policy layer that was not the Sheets API, the file permissions, or the user.
Where it’s from
Summarized from a public post on discuss.google.dev. See the original ↗