Bug and fix: LiteLLM Connection Fails with Trailing Slash in Base URL

[kcwhite]

App Version

3.19.3

API Provider

LiteLLM

Model Used

bedrock-us.anthropic.claude-3-7-sonnet-20250219-v1:0

🔁 Steps to Reproduce

Description

When configuring Roo Code to connect to a LiteLLM server with a base URL that includes a trailing slash, the connection fails because the API endpoint is constructed incorrectly, resulting in a double slash in the URL path.

Steps to Reproduce

1. Open Roo Code
2. Click on the Settings icon (gear) in the Roo Code panel header
3. Select "Providers" from the settings menu
4. Click "API Provider"
5. Select "LiteLLM" from the provider dropdown
6. In the "Base URL" field, enter a URL with a trailing slash (e.g., "http://localhost:4000/")
7. Enter your API key in the "API Key" field
8. Click "Save"
9. Click "Refresh Models"
10. Observe the error "Failed to fetch LiteLLM models: 404 Not Found. Check base URL and API key."

Expected Behavior

Roo Code should successfully connect to the LiteLLM server regardless of whether the base URL contains a trailing slash.

Actual Behavior

The connection fails because the API endpoint is constructed as "http://localhost:4000//v1/model/info" (note the double slash), which is not a valid URL path.

Additional Information

This issue occurs because the base URL is directly concatenated with the endpoint path without checking for or handling trailing slashes, resulting in malformed URLs when users include a trailing slash in their configuration.

💥 Outcome Summary

Expected to connect to corporate LiteLLM gateway, but got a 404 Not Found Error instead. Credentials were valid.

📄 Relevant Logs or Errors (Optional)

Failed to fetch LiteLLM models: 404 Not Found. Check base URL and API key.

[dosubot]

Hi @kcwhite! I'm Dosu and I’m helping the Roo-Code team.

You are correct—Roo Code currently constructs the LiteLLM API endpoint by directly concatenating the base URL with /v1/model/info, which causes a double slash (//) if the base URL ends with a trailing slash. This results in a malformed URL and a 404 error from the LiteLLM server, even when credentials are valid and the server is reachable. The documentation confirms this construction method but does not mention any handling for trailing slashes or provide a built-in solution for this issue (source).

There is no official workaround documented, nor any configuration setting to automatically handle or strip trailing slashes. The best way to avoid this issue is to ensure that the base URL you enter in the LiteLLM provider settings does not end with a trailing slash (e.g., use http://localhost:4000 instead of http://localhost:4000/). This will allow Roo Code to construct the correct endpoint and connect successfully.

If you need to use a trailing slash for some reason, you would need to remove it manually before saving the configuration, as there is currently no automatic handling for this case in Roo Code.

If you have any further questions or need more details about LiteLLM integration, let me know!

To reply, just mention my name @dosu.

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