RAGFlow MCP server not accepting user API Key

[Odrec]

What happened?

I set up a RAGFLow MCP server in host mode: https://ragflow.io/docs/dev/launch_mcp_server

I can confirm it works properly using curl from the librechat server.

[librechat]$ curl -H "Authorization: Bearer ragflow-NiYTQzKjljNmM1NjExZjBjHTZiNmFkND"      https://ragflow.virt.uos.com/sse
event: endpoint
data: /messages/?session_id=953d7cd5d3724b1dbf26992184e36be1

This is not the actual API key but it's the same length and format.

I configured the MCP server like this in librechat.yaml:

mcpServers:
  ragflow:
    type: sse
    url: https://ragflow.virt.uos.com/sse
    headers:
      Authorization: "Bearer {{API_KEY}}"
    timeout: 30000
    serverInstructions: true
    customUserVars:
      API_KEY:
        title: "RAGFlow API Key"
        description: "Your personal RAGFlow API key for accessing knowledge bases. You can find or generate your API key in the RAGFlow web interface."
    startup: false

The MCP server shows up and I can enter the key in the UI but then when I hit Save button it switches to Saving... and it'S greyed out and it remains there.

Looking at the Librechat logs I only see this that I assume is related:

2025-08-07 10:36:00 info: [MCP Reinitialize] Reinitializing server: ragflow
2025-08-07 10:36:00 info: [MCP Reinitialize] Disconnected existing server: ragflow
2025-08-07 10:36:00 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Establishing new connection
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Access token missing
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Access token missing and no refresh token available
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Creating SSE transport: https://ragflow.virtuos.uni-osnabrueck.de/sse
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Connection successfully established
2025-08-07 10:36:01 info: [MCP Reinitialize] Successfully established connection for ragflow
2025-08-07 10:36:07 error: [updateUserPluginAuth] Invalid key length
2025-08-07 10:36:07 error: [authService] Invalid key length
2025-08-07 10:36:07 error: [updateUserPluginsController] Invalid status code: undefined

Version Information

sudo docker images | grep librechat
ghcr.io/danny-avila/librechat-rag-api-dev latest 0e8a1478bb84 41 hours ago 7.87GB
ghcr.io/danny-avila/librechat-dev latest e05ac102518f 2 days ago 1.17GB
ghcr.io/librechat-ai/codesandbox-client/bundler latest e61e659c0210 6 days ago 152MB
ghcr.io/virtuos/librechat_exporter 2.1.0 db9e0104d6af 2 months ago 283MB

Steps to Reproduce

1. Install RAGFLow MCP server in host mode
2. Configure in Librechat
3. Try to enter your API Key

What browsers are you seeing the problem on?

No response

Relevant log output

2025-08-07 10:36:00 info: [MCP Reinitialize] Reinitializing server: ragflow
2025-08-07 10:36:00 info: [MCP Reinitialize] Disconnected existing server: ragflow
2025-08-07 10:36:00 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Establishing new connection
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Access token missing
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Access token missing and no refresh token available
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Creating SSE transport: https://ragflow.virtuos.uni-osnabrueck.de/sse
2025-08-07 10:36:01 info: [MCP][User: 68122240d5bdaf39458ca507][ragflow] Connection successfully established
2025-08-07 10:36:01 info: [MCP Reinitialize] Successfully established connection for ragflow
2025-08-07 10:36:07 error: [updateUserPluginAuth] Invalid key length
2025-08-07 10:36:07 error: [authService] Invalid key length
2025-08-07 10:36:07 error: [updateUserPluginsController] Invalid status code: undefined

Screenshots

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[dustinhealy]

I am having a bit of trouble following your steps to install ragflow in order to replicate and diagnose your issue, however in the meantime, can you confirm that customUserVars are working when you save them for any other MCP servers? I believe the error you are getting would only come up if the CREDS_KEY field in your .env was malformed / unset. Can you confirm that it is populated properly with a 32-byte hexadecimal value?

[Odrec]

I am having a bit of trouble following your steps to install ragflow in order to replicate and diagnose your issue, however in the meantime, can you confirm that customUserVars are working when you save them for any other MCP servers? I believe the error you are getting would only come up if the CREDS_KEY field in your .env was malformed / unset. Can you confirm that it is populated properly with a 32-byte hexadecimal value?

We have been using LibreChat in production for 2 years now and have always have the same CREDS_KEY so I don't think that's the issue. Nevertheless this is the first attempt we make with MCP servers so we actually don't have any other installed. Do you have one to recommend I can try that you know that works?

[dustinhealy]

filesystem or the everything MCP servers are my default test beds, you can just add generic customUserVars to them in order to verify the issue is not specific to the RAGFlow MCP.

Just want to clarify a point on your last message - you confirmed the CREDS_KEY length was a 32-byte (64 chars) hexadecimal?

PR opened to stop what I believe is causing the UI hang when a malformed CREDS_KEY is supplied.

[Odrec]

filesystem or the everything MCP servers are my default test beds, you can just add generic customUserVars to them in order to verify the issue is not specific to the RAGFlow MCP.

Just want to clarify a point on your last message - you confirmed the CREDS_KEY length was a 32-byte (64 chars) hexadecimal?

PR opened to stop what I believe is causing the UI hang when a malformed CREDS_KEY is supplied.

Oh wow, I missed the hexadecimal part. It was a 32 byte string but it had some letters outside the hexadecimal scope. After changing it, it works! Thank you so much!