Set up sign-in for managed MCP servers changedthird-party/claude-desktop/mcp-sign-in
Nearest release: v2.1.322, published 20 hours before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Upstream edited this page at 10 Nov 2026 22:26 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 10 Nov 2026 22:37 UTC.
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16 Sep 2026
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Recorded edits8to this page, all time
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9090| What the user sees or `main.log` records | Cause | Fix |
9191| - | - | - |
92| "Connection to server failed. You can try again." with no sign-in window, and `main.log` shows an HTML block page from your network, starting at the `[error]` line that contains the server's name and the word `failed` | A firewall or secure web gateway blocked the request to the MCP server before sign-in started. Such equipment can classify the connection as Model Context Protocol (MCP) traffic and block it even when the server's host is allowed | Send the block page to your network team and ask them to allow MCP traffic to the server's host. Then have the user click **Connect** again |
92| Either "Couldn't connect to \{server}. Try again later. If it keeps failing, ask your IT admin whether a firewall or proxy is blocking MCP traffic." (Claude Desktop 5.1231.0 or later) or "Connection to server failed. You can try again.", with no sign-in window, and `main.log` shows an HTML block page from your network, starting at the `[error]` line that contains the server's name and the word `failed` | A firewall or secure web gateway blocked the request to the MCP server before sign-in started. Such equipment can classify the connection as Model Context Protocol (MCP) traffic and block it even when the server's host is allowed | Send the block page to your network team and ask them to allow MCP traffic to the server's host. Then have the user click **Connect** again |
93| `main.log` shows `Unexpected content type: text/html` on the `[error]` line that contains the server's name and the word `failed` | The request got a web page with a success status in place of the MCP server's response, and `main.log` didn't record the page. The page can be a block page from your network or a website that the entry's **URL** points to | Check that the entry's **URL** is the MCP server's endpoint. If it is, ask your network team whether a firewall or secure web gateway blocks MCP traffic to the server's host. If one does, ask them to allow that traffic |
9394| "Couldn't connect to \{server} because it doesn't support automatic client registration" (Claude Desktop 2.110.0 or later), or `main.log` records that the authorization server does not support dynamic client registration | **OAuth** is **Auto-register** but the identity provider requires a client that you register | Register a public client with redirect URI `http://127.0.0.1:53280/callback`, set **OAuth** to **Bring your own client**, and fill in **Client ID** |
9495| The browser step succeeds, then the connection fails and `main.log` records the token endpoint's error, for example `client_secret is missing` | The entry has a **Client ID** but the identity provider also requires the secret | Add the secret and **Authorization server** as described under [Where the client secret goes](#where-the-client-secret-goes) |
9596| `main.log` names a rejected referrer host during sign-in | The identity provider completes sign-in from a host other than the one in its authorization URL | Add that hostname to **Additional redirect referrer hosts** |
No line in this hunk matches that.