Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
One of my three Cursor Projects shows “Couldn’t sync Project context” in the Project / Context panel. Chat and cloud agents for that Project still work. The other two Projects sync normally.
From Cursor Agent Exec, the local sync client refuses to mount that Project’s agent store because the cloud index is schema version 5 and this client does not support it:
[info] [agent-store-sync] mount u53998004 failed: Unsupported agent store index schema version: 5 (next retry in 51s)
[info] [cursor-agent-exec] principal mount skipped alias=user outcome=not-started reason=index-schema-unsupported
[info] [cursor-agent-exec] principal mount skipped alias=user outcome=cooling-down reason=mount-backoff
This started after a recent Cursor update (Check for Updates already says I’m up to date). The broken Project is my most-used / most-written Project (cloud agents + Notes). The two quieter Projects still sync, which fits a per-Project cloud store that was migrated to schema 5 while the desktop client still can’t mount that schema.
Steps to Reproduce
Open the affected Project in the Agents Window.
Open the Project / Context panel → “Couldn’t sync Project context.”
Open a normal editor window → View → Output → Cursor Agent Exec → see the schema version 5 / index-schema-unsupported lines above.
Open either of my other two Projects → Context sync works.
Expected Behavior
Desktop client can mount / sync Project context for any Project store schema the cloud is writing, or cloud should not advance a Project to an unsupported schema for Stable clients.
Operating System
MacOS
Version Information
Cursor reports up to date via Check for Updates. Issue began after a recent update.
For AI issues: which model did you use?
Opus 5.5
Does this stop you from using Cursor
No - Cursor works, but with this issue