Autocomplete and Chat Fail Depending on HTTP Protocol Version

[Roma_Roma]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

When using HTTP/2, the chat feature works fine, but autocomplete is broken (no suggestions appear). When switching to HTTP/1.1 or HTTP/1.0, autocomplete functions correctly, but the chat fails to load or respond.

Steps to Reproduce

Open Cursor and ensure you’re connected to the internet.

Go to Cursor Settings > Network

Set protocol to HTTP/2:

Chat: Works (messages send/receive normally).

Autocomplete: Broken (no inline suggestions on typing).

Switch protocol to HTTP/1.1 or HTTP/1.0:

Chat: Fails (no response, errors, or connection timeout).

Autocomplete: Works perfectly.

Restart Cursor and reproduce—issue persists.

Expected Behavior

Both chat and autocomplete should work regardless of HTTP protocol (1.0/1.1/2).

Operating System

Windows 10/11

Version Information

Version: 2.6.14 (user setup)
VSCode Version: 1.105.1
Commit: eb1c4e0702d201d1226d2a7afb25c501c2e56080
Date: 2026-03-08T15:36:54.709Z
Build Type: Stable
Release Track: Default
Electron: 39.6.0
Chromium: 142.0.7444.265
Node.js: 22.22.0
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.19045

For AI issues: which model did you use?

Any

For AI issues: add Request ID with privacy disabled

Request ID: bdf60d6f-ec7b-4854-996d-f8e672b85287
{“error”:“ERROR_NETWORK_ERROR”,“details”:{“title”:“Network Error”,“detail”:“Unexpected seqno: 2 != 1. Please try again, or contact support if the issue persists.”,“isRetryable”:true,“additionalInfo”:{},“buttons”:,“planChoices”:},“isExpected”:false}
[unavailable] Unexpected seqno: 2 != 1. Please try again, or contact support if the issue persists.
hie: [unavailable] Unexpected seqno: 2 != 1. Please try again, or contact support if the issue persists.
at o5A (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:34244:23755)
at r5A (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:34244:22658)
at m5A (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:34245:6285)
at kou.run (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:34245:10400)
at async _Oa.runAgentLoop (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46808:10024)
at async N3u.streamFromAgentBackend (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46862:9277)
at async N3u.getAgentStreamResponse (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:46862:13663)
at async bMe.submitChatMaybeAbortCurrent (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:34305:17597)
at async Ea (vscode-file://vscode-app/c:/Users/User/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:45787:4826)

Additional Information

Problem did not exist before version 2.3.x.

Does this stop you from using Cursor

Yes - Cursor is unusable

[deanrie]

Hey, thanks for the detailed report.

The “Unexpected seqno: 2 != 1” error is an HTTP/2 stream sequencing issue. It usually happens when something between your machine and our servers, like a VPN, proxy, antivirus, or corporate firewall, interferes with HTTP/2 multiplexing.

It’s unusual that Tab breaks on HTTP/2 but chat breaks on HTTP/1.1. A few questions to narrow this down:

• Are you behind a VPN or corporate proxy, or using antivirus software with web filtering (like Zscaler, Kaspersky, ESET, etc.)?
• Can you run Cursor Settings > Network > Run Diagnostics and share the results? Please run it once with HTTP/2 enabled and once with it disabled.
• Does the issue still happen on a different network, like a mobile hotspot?

Also worth trying:

• Make sure you’re on the latest version. 2.6.18 is current, you’re on 2.6.14.
• In App Settings (Ctrl + ,), search for cursor.general.disableHttp2 and set it to true. This is separate from the Network diagnostics toggle and it specifically affects Tab and Inline Edit.

Your request ID is logged. Let me know your answers and we’ll go from there.

[Roma_Roma]

Cursor updates frequently, and each time either chat or Tab autocomplete breaks for me—alternating functionality depending on HTTP protocol settings. How should I handle this reliably?

This month alone, hangs burned through all my tokens (previously no issue). Chat responds to the first message then freezes while “reading files.”

No VPN/antivirus,. Diagnostics clean now on 2.6.18 (both HTTP/2 and 1.1 work temporarily), but I’m dreading the next update regression.