Cursor Extension Host Crashes on macOS 26.2

[davecotter (Davina Cotter)]

### github issue posted

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cursor Extension Host Crashes on macOS 26.2

Summary

Cursor’s extension host process crashes consistently ~47-54 seconds after startup on macOS 26.2, preventing the AI agent (cursor-agent-exec extension) from initializing properly. This results in the agent hanging at “planning next moves” with no response.

Environment

• OS: macOS 26.2
• Cursor Version: 2.2.43 (Electron 37.7.0)
• Machine: libre.local (Mac)
• Workspace: /Volumes/extra/scripts/kjams.com.code-workspace (95GB, 23,708 files)
• macOS Build: darwin 25.1.0 (kernel version suggests 26.2)

Steps to Reproduce

1. Launch Cursor on macOS 26.2
2. Wait 47-54 seconds after startup
3. Extension host crashes with exit code 5
4. Attempt to use AI agent (e.g., ask “are you there”)
5. Agent hangs at “planning next moves” with no response

Expected Behavior

• Extension host should remain stable
• AI agent should initialize and respond to queries
• Agent log file should contain initialization and activity logs

Actual Behavior

1. Extension host starts successfully (PID assigned)
2. Extensions begin activating (cursor-agent-exec, cursor-mcp, etc.)
3. After ~47 seconds, extension host becomes unresponsive
4. Extension host crashes with exit code 5 after ~54 seconds
5. Extension host auto-restarts but crashes again in the same pattern
6. cursor-agent-exec extension log file remains empty (0 bytes)
7. When querying AI agent, Renderer process CPU spikes to 100%
8. Agent hangs at “planning next moves” with no response

Log Evidence

2025-12-26 14:36:10.535 [info] Started local extension host with pid 5795.
2025-12-26 14:36:12.153 [info] ExtensionService#_doActivateExtension anysphere.cursor-agent-exec
2025-12-26 14:36:57.844 [info] Extension host (LocalProcess pid: 5795) is unresponsive.
2025-12-26 14:37:04.945 [info] Extension host with pid 5795 exited with code: 5, signal: unknown.
2025-12-26 14:37:04.946 [error] [UtilityProcess id: 1, type: extensionHost, pid: 5795]: crashed with code 5

Root Cause

The extension host crashes before cursor-agent-exec can fully initialize. The agent log file (Cursor Agent Exec.log) remains at 0 bytes, indicating the extension never successfully starts its logging or initialization routines.

This is a known compatibility issue between Cursor (Electron 37.7.0) and macOS 26.2. The crash occurs in the UtilityProcess extension host, suggesting an OS-level incompatibility or Electron framework issue with macOS 26.2.

Impact

• Critical: AI agent functionality is completely unusable
• Extension host crashes in a continuous restart loop
• High CPU usage (100% on Renderer when attempting to use agent)
• No error messages shown to user, only silent hanging

Workarounds Attempted (None Successful)

1. Cleared extension caches
2. Updated Cursor settings (file watcher exclusions, experimental flags)
3. Signed out and signed back into Cursor (authentication fix)
4. Launched with --disable-gpu flag (made it worse - GPU process consumed 100% CPU with SwiftShader software rendering)
5. Disabled problematic extensions
6. Verified network connectivity (not a network issue)
7. Verified workspace file paths (file watcher errors present but not root cause)

Additional Information

• Same Cursor version works correctly on pandora machine (different macOS version)
• Extension host crashes are consistent and reproducible
• Crash timing is predictable (~47-54 seconds after startup)
• No user-facing error messages - only log entries
• Related forum discussion: Cursor Extension Host Crashes on macOS 26.1 (Tahoe) - Nightly Build

Requested Fix

Update Cursor to be compatible with macOS 26.2, or provide guidance on workarounds that actually work.

System Information

Processes: 675 total, 28 running, 1 stuck, 646 sleeping
Load Avg: 38.70, 17.11, 11.42
CPU usage: 47.35% user, 52.64% sys, 0.0% idle
PhysMem: 24G used

Files Affected

• ~/Library/Application Support/Cursor/logs/*/window1/exthost/exthost.log
• ~/Library/Application Support/Cursor/logs/*/window1/exthost/anysphere.cursor-agent-exec/Cursor Agent Exec.log (0 bytes)
• ~/Library/Application Support/Cursor/logs/*/main.log

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Report Date: 2025-12-26
Severity: Critical
Priority: High (blocks core functionality)

Steps to Reproduce

macos 26.2
run cursor
attempt query

Expected Behavior

query answered

Screenshots / Screen Recordings

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.2.43
VSCode Version: 1.105.1
Commit: 32cfbe848b35d9eb320980195985450f244b3030

For AI issues: which model did you use?

auto

Does this stop you from using Cursor

Yes - Cursor is unusable

[sanjeed5 (Sanjeed)]

Thanks for the detailed report, I’ve raised it with the team.