[Bug]: Mattermost Desktop v6.1.2 on Windows 11 using 80%+ of CPU

[hfickes]

Checks before filing an issue

• This issue doesn't reproduce on web browsers (such as in Chrome). If it does, issue reports go to the Mattermost Server repository.
• I have checked the issue tracker and have not found an issue that matches the one I'm filing. This should include closed issues.
• This issue is not a troubleshooting question. Troubleshooting questions go here: https://forum.mattermost.com/c/trouble-shoot/16.
• This issue is not a feature request. You can request features and make product suggestions here: https://mattermost.com/suggestions/.
• This issue reproduces on the most recent stable version, or the most recent prerelease version of the Mattermost Desktop App.
• I have read the contribution guidelines.

Mattermost Desktop Version

6.1.2

Operating System

Windows 11 x64 with all updates

Mattermost Server Version

10.7.1

Steps to reproduce

Even when running almost nothing on my Windows laptop, Mattermost will take nearly all the CPU and the generated heat causes the fan to run constantly. It takes about 5 to 15 minutes for it to happen. Typically Mattermost desktop consumes 70-80% of CPU, sometimes higher.

The task manager shows 12-33 Mattermost Desktop processes. This is with one team consisting of 7 channels.

Running mattermost from the Edge, Chrome, and Firefox browsers does not do this.

This is with Mattermost Desktop v6.1.2 on Windows 11 (all available updates as of May 2026)

Expected behavior

Mattermost shouldn't consume more than a small amount of CPU. Mattermost Desktop prior to v6.1.2 rarely did this. Now it is constant.

Observed behavior

CPU is nearly entirely taken by MM desktop, 92% as I write this. It also uses much of memory.

Log Output

[2026-05-12 14:28:49.369] [error] [WebContentsEventM...] [e64c531c-4097-48c...] [c0f9ebe2-36ac-472...] [renderer] Access to XMLHttpRequest at 'https://pdat.matterlytics.com/v1/track' from origin 'https://<host>' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
[2026-05-12 14:30:54.333] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 14:35:30.360] [error] [WebContentsEventM...] [e64c531c-4097-48c...] [c0f9ebe2-36ac-472...] [renderer] Access to XMLHttpRequest at 'https://pdat.matterlytics.com/v1/track' from origin 'https://<host>' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
[2026-05-12 14:35:30.383] [error] [WebContentsEventM...] [e64c531c-4097-48c...] [c0f9ebe2-36ac-472...] [renderer] Access to XMLHttpRequest at 'https://pdat.matterlytics.com/v1/track' from origin 'https://<host>' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
[2026-05-12 14:35:31.508] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:09:35.041] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:12:11.298] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:12:14.489] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:19:32.010] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:27:58.081] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:36:21.342] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:40:14.660] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:46:09.864] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:47:24.375] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 15:48:44.471] [error] [App.App] "child-process-gone" The child process has crashed. Details:  {
  details: {
    type: 'Utility',
    reason: 'crashed',
    exitCode: -1073740791,
    serviceName: 'proxy_resolver.mojom.ProxyResolverFactory',
    name: 'V8 Proxy Resolver'
  }
}
[2026-05-12 16:17:04.118] [error] [WebContentsEventM...] [e64c531c-4097-48c...] [c0f9ebe2-36ac-472...] [renderer] Access to XMLHttpRequest at 'https://pdat.matterlytics.com/v1/track' from origin 'https://<host>' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Additional Information

[devinbinnie]

So I'm not able to reproduce this behaviour myself, with two servers running I'm only at 13 processes. My guess is that the repeated crashing is causing some processes to re-launch and the previous ones to get stuck.

What might help to see is what processes are actually running by adding the Command Line column to Task Manager and expanding the process tree so I can see what's happening. See my screenshot:

As for the root cause, I would wager that something on your machine, or your server configuration is causing the constant crashes. That utility process is internal to Electron and is part of the V8 engine so it isn't something our app specifically controls. It would be worth seeing if there are any conflicts with any endpoint management software, or checking if there is a proxy configuration that's causing an issue here.

[hfickes]

I'll reinstall v6 and get the trace you ask for tomorrow.

However, even if there are conflicts with endpoint software or a proxy confg issue, why should Mattermost be consuming 90+% of the CPU under any circumstance?

[devinbinnie]

I'll reinstall v6 and get the trace you ask for tomorrow.

However, even if there are conflicts with endpoint software or a proxy confg issue, why should Mattermost be consuming 90+% of the CPU under any circumstance?

It shouldn't be. I'm guessing the large number of processes has something to do with that.