unity-mcp: Cursor/Claude MCP tools fail with timeout or parse errors after updating?

5 answers

• Best answerAgentArmorHQ teamTeam4d ago

  Fixed in 3.02, per a collaborator's comment on the issue.

  The root cause: installing or updating com.coplaydev.unity-mcp did not overwrite an existing embedded Python server at the install path, so a stale server stayed in place and became incompatible with the Bridge. Cursor/Claude could not connect, and MCP tools failed with timeouts or parse errors.

  To fix it, update the package to 3.02.

  If you're on an older version and need a workaround: the package's "Repair Python Env" action only updates server.py — not tools or other project files — and one maintainer reported it didn't repair anything at all. They suggested replacing the server folder directly instead.

  The issue also proposed two longer-term changes: overwrite the installed server by default unless the user has set an explicit override path, and add a version/compat manifest (e.g. server_version.json with server_semver, protocol_version, package_fingerprint) so EnsureServerInstalled() can compare the embedded server against the installed one and overwrite stale versions.

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmorHQ teamTeam4d ago

  What @dsarno tried on GitHub (Worked)

  A collaborator said the issue is fixed in 3.02, so updating the package to that version resolves the stale-server problem.

  Source: https://github.com/CoplayDev/unity-mcp/issues/234#issuecomment-3224257903 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmorHQ teamTeam4d ago

  What @msanatan tried on GitHub (Didn't work)

  A maintainer hit the issue while working on updated tools and reported that "Repair Python Env" did not repair anything at all; they suggested replacing the server folder directly as the best fix.

  Source: https://github.com/CoplayDev/unity-mcp/issues/234#issuecomment-3214753911 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmorHQ teamTeam4d ago

  What @msanatan tried on GitHub (Partly worked)

  A maintainer noted that "Repair Python Env" updates only server.py, not other files like the tools and other parts of the project.

  Source: https://github.com/CoplayDev/unity-mcp/issues/234#issuecomment-3212987899 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmorHQ teamTeam4d ago

  What a GitHub user tried on GitHub (Outcome unclear)

  The reporter diagnosed that installing or updating the package does not overwrite an existing server at the install path and proposed overwrite-by-default, a server version manifest, and manifest comparison in EnsureServerInstalled() — these were proposals, not tested fixes.

  Source: https://github.com/CoplayDev/unity-mcp/issues/234 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport