Bug Report: Cursor Crashes and System Freezes When Opening Agent Window on macOS

Support Bug Reports
, ,
1

Dear Cursor Support Team, I am writing to report a critical issue I have been experiencing with Cursor. First of all, I am a developer from China and a big fan of Cursor. I genuinely enjoy using this software and recently upgraded to Cursor Pro earlier this month to support your work. However, I have encountered a severe issue that is currently blocking my daily workflow. System Information: OS: macOS 15.7.1 App Version: [latest]

When I first launch Cursor, everything works normally, and Activity Monitor shows no abnormalities. However, as soon as I click any buttons related to the Agent window (such as opening or creating a new Agent window), the window immediately crashes and fails to open. Retrying the action results in the same behavior. Each attempt causes both memory usage and CPU utilization to spike dramatically, eventually leading to a complete system freeze. Steps to Reproduce: Launch Cursor. Click on any button related to opening or creating a new Agent window. The window crashes instantly, and system resources (CPU and RAM) surge until the system freezes. I have attached relevant logs/screenshots for your reference. As a Pro user who relies heavily on the Agent feature, I would greatly appreciate it if you could look into this issue promptly. Thank you for your assistance, and keep up the great work!

Best regards,

kirito

2

Hi there!

We detected that this may be a bug report, so we’ve moved your post to the Bug Reports category.

To help us investigate and fix this faster, could you edit your original post to include the details from the template below?

Bug Report Template - Click to expand

Where does the bug appear (feature/product)?

  • Cursor IDE
  • Cursor CLI
  • Background Agent (GitHub, Slack, Web, Linear)
  • BugBot
  • Somewhere else…

Describe the Bug
A clear and concise description of what the bug is.

Steps to Reproduce
How can you reproduce this bug? We have a much better chance at fixing issues if we can reproduce them!

  1. …
  2. …
  3. …

Expected Behavior
What is meant to happen here that isn’t working correctly?

Screenshots / Screen Recordings
If applicable, attach images or videos (.jpg, .png, .gif, .mp4, .mov)

Operating System

  • Windows 10/11
  • MacOS
  • Linux

Version Information

  • For Cursor IDE: Menu → About Cursor → Copy
  • For Cursor CLI: Run agent about in your terminal
IDE:
Version: 2.xx.x
VSCode Version: 1.105.1
Commit: ......

CLI:
CLI Version 2026.01.17-d239e66

For AI issues: which model did you use?
Model name (e.g., Sonnet 4, Tab…)

For AI issues: add Request ID with privacy disabled
Request ID: f9a7046a-279b-47e5-ab48-6e8dc12daba1
For Background Agent issues, also post the ID: bc-…

Additional Information
Add any other context about the problem here.

Does this stop you from using Cursor?

  • Yes - Cursor is unusable
  • Sometimes - I can sometimes use Cursor
  • No - Cursor works, but with this issue

The more details you provide, the easier it is for us to reproduce and fix the issue. Thanks!

4

Cursor IDE

just open the cursor ide and click the agent window

macos 15

Yes - Cursor is unusable,but cursor on windows 11 is ok

6

Steps to Reproduce:
I have successfully isolated the exact steps to reproduce this bug:

  1. Go to Agent Settings.
  2. Set the “Max Tab Count” to 1.
  3. Return to the Agent window and click the “+” button to create a new tab.
  4. The window crashes instantly, and system resources (CPU and RAM) surge until the system freezes.
7

Hey, thanks for the report and especially for isolating the steps. This is a known issue. When Max Tab Count = 1, creating a new tab via the + button can crash the Agents Window with a sharp CPU and RAM spike. We’re tracking it, but I can’t share an exact ETA for a fix yet.

Workaround for now: open Agent Settings and increase Max Tab Count to more than 1, for example the default value. After that, creating new tabs and opening the Agent window should work without crashing.

Let me know if it still happens after raising the limit, and we’ll dig deeper.

8

same issue here., it freezes my whole mac and I already have 48 GB ram

9

Hey, thanks for the report. This might be the same case as above: a crash when Max Tab Count = 1 and you create a new tab. It’s a known issue and we don’t have an ETA for a fix yet.

First, try this workaround: open Agent Settings and set Max Tab Count to more than 1, like the default value. After that, opening the Agent window and creating new tabs should work without crashing.

If your Max Tab Count isn’t 1 and it still crashes, it’s likely a different scenario. Please send:

  • your Cursor version Menu > About Cursor > Copy
  • how many MCP servers are enabled Settings > MCP or ~/.cursor/mcp.json

Opening the Agent window initializes all enabled MCP servers at once, and a heavy or slow server can cause the renderer to run out of memory and crash. Try temporarily disabling MCP servers and see if the freeze still happens.

Let me know how it goes.