Remote MCP Servers not working since v0.15 #2091

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opened 2026-02-16 17:34:06 -05:00 by yindo · 6 comments
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Originally created by @williamjvest on GitHub (Oct 13, 2025).

Originally assigned to: @thdxr on GitHub.

Since v.0.15 I cannot get remote MCP servers to work. Continues to give this error "UnknownError MCP server fireflies failed to connect: SSE error: Non-200 status code (403)". That example is just with fireflies but my other remote server continues to have issues as well.

Originally created by @williamjvest on GitHub (Oct 13, 2025). Originally assigned to: @thdxr on GitHub. Since v.0.15 I cannot get remote MCP servers to work. Continues to give this error "UnknownError MCP server fireflies failed to connect: SSE error: Non-200 status code (403)". That example is just with fireflies but my other remote server continues to have issues as well.
yindo closed this issue 2026-02-16 17:34:06 -05:00
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@github-actions[bot] commented on GitHub (Oct 13, 2025):

This issue might be a duplicate of existing issues. Please check:

  • #834: Remote MCP servers using Server-Sent Events (SSE) fail to start with 'UnknownError Server error' - both involve SSE transport failures for remote MCP servers, though #834 focuses on general SSE support while this appears to be a v0.15 regression

Feel free to ignore if none of these address your specific case.

@github-actions[bot] commented on GitHub (Oct 13, 2025): This issue might be a duplicate of existing issues. Please check: - #834: Remote MCP servers using Server-Sent Events (SSE) fail to start with 'UnknownError Server error' - both involve SSE transport failures for remote MCP servers, though #834 focuses on general SSE support while this appears to be a v0.15 regression Feel free to ignore if none of these address your specific case.
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@rekram1-node commented on GitHub (Oct 13, 2025):

Do these mcp servers require Oauth flow?

@rekram1-node commented on GitHub (Oct 13, 2025): Do these mcp servers require Oauth flow?
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@williamjvest commented on GitHub (Oct 13, 2025):

Both have the option, but both also have the option of using an API key which is how I have it setup.

@williamjvest commented on GitHub (Oct 13, 2025): Both have the option, but both also have the option of using an API key which is how I have it setup.
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@rekram1-node commented on GitHub (Oct 13, 2025):

hm okay

@rekram1-node commented on GitHub (Oct 13, 2025): hm okay
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@williamjvest commented on GitHub (Oct 13, 2025):

I just did a fresh install on another machine and it setup and connected just fine. So I must have an issue elsewhere in my setup. Apologies.

@williamjvest commented on GitHub (Oct 13, 2025): I just did a fresh install on another machine and it setup and connected just fine. So I must have an issue elsewhere in my setup. Apologies.
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@rekram1-node commented on GitHub (Oct 13, 2025):

no problem!

@rekram1-node commented on GitHub (Oct 13, 2025): no problem!
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Reference: anomalyco/opencode#2091