Http2 network error with cursor ide and cursor-cli

[dartemage]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

During diagnostics from a network using Google DNS 8.8.8.8, if you ping agent.api5.cursor.sh, it resolves to

agent.api5.cursor.sh.cdn.cloudflare.net - 104.18.19.125

Directly accessing the link results in ERR_SSL_VERSION_OR_CIPHER_MISMATCH, and the IDE shows errors as in the screenshot. The likely cause is incorrectly configured SSL certificates: Fix VERSION_OR_CIPHER_MISMATCH · Cloudflare SSL/TLS docs
.

When using Quad9 DNS 149.112.112.112,

ping resolves to

agent.api5latency-useast.cursor.sh - 100.30.166.181

and there are no SSL issues; HTTP/2 works correctly. Therefore, the problem is related to Cloudflare settings.

There is also an issue in cursor-cli where some requests use an HTTP/2 approach, even though it is explicitly disabled in the settings, so it cannot be used reliably at this time.

My IP is from Ukraine, and DNS resolution may differ when queried from another region.

Steps to Reproduce

as described above

Screenshots / Screen Recordings

Operating System

Windows 10/11
MacOS
Linux

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.2.43 (system setup)
VSCode Version: 1.105.1
Commit: 32cfbe848b35d9eb320980195985450f244b3030
Date: 2025-12-19T06:06:44.644Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.19045

Does this stop you from using Cursor

Yes - Cursor is unusable

[sanjeed5 (Sanjeed)]

Thanks for the detailed report. Since switching to Quad9 DNS fixes the SSL issue - does that workaround also resolve the cursor-cli problem, or does the CLI still fail even with Quad9?

If the CLI still has issues, what command are you running and what error do you see?

I’ve also raised this issue with the team

[dartemage]

If I use this DNS (the specific one is not important; the key point is that the routing does not go through Cloudflare), the issue disappears both in the IDE and in the CLI.

Since this problem is related to the network rather than the tool itself, it is necessary to verify that SSL is correctly configured on the server side.