Azure / Azure/Azure-Resource-Manager-MCP

[Bug]: Cannot call MCP server - returns 504 gateway timeout

Open

#25 opened on Aug 29, 2026 1 comment 0 reactions 0 assignees View on GitHub

bug

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Merged PRs (30d): 1

Description

### Description

When making a curl request to mcp server curl.exe -i https://mcp.resource-mcp-test.azure.com/mcp we get the following response:
```
HTTP/1.1 504 Gateway Time-out
Date: Sat, 29 Aug 2026 22:39:30 GMT
Content-Type: text/html
Content-Length: 2061
Connection: keep-alive
Cache-Control: no-store
x-azure-ref: 20260829T223922Z-1659c4cb8949j7d6hC1STOhsg80000000ft0000000007z3z
X-Cache: CONFIG_NOCACHE

body {
font-family: Arial;
margin-left: 40px;
}

img {
border: 0 none;
}

#content {
margin-left: auto;
margin-right: auto
}

#message h1 {
font-size: 24px;
font-weight: normal;
color: #000000;
margin: 34px 0px 0px 0px
}

#message h2 {
font-size: 20px;
font-weight: normal;
color: #000000;
margin: 34px 0px 0px 0px
}

#message p {
font-size: 16px;
color: #000000;
margin: 8px 0px 0px 0px
}

#message hr {
margin: 15px 0px
}

#errorref {
font-size: 11px;
color: #737373;
margin-top: 41px
}

Service unavailable

504

The service behind this page isn't responding to Azure Front Door.

Gateway Timeout

```

### Steps to Reproduce

Run curl from your local machine.
curl.exe -i https://mcp.resource-mcp-test.azure.com/mcp

### Expected Behavior

Expected to get 401 unauthorized back or something that says that we did indeed hit the backend behind Front Door

### Actual Behavior

Get 504 gateway timeout back from Front Door

### VSCode Version

None

### ARM MCP Server Version

Just calling the url so the latest

### Model Being Used

GTP 5 mini from Azure AI Foundry

### Trace ID

_No response_

### Logs / Screenshots

```text

```

### Additional Context

Call the MCP server from AI Foundry as a custom MCP tool.

Contributor guide

Open the contributing guide

Research direction

Start by reproducing the request with curl.exe against https://mcp.resource-mcp-test.azure.com/mcp and use the reported Azure Front Door response as the baseline. Trace why the MCP endpoint is not responding through Front Door; done means the endpoint reaches the backend and returns an authentication response such as 401 instead of a 504 timeout.

Written by the indexing model from the issue text.

Assessment

Tech stack: azure
Domain: api, cloud
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Active
Clarity: Mostly clear
Newbie friendliness: 48/100