MCP fixes
ChatGPT MCP connect: blank page or won't connect
A ChatGPT custom MCP connector that opens a blank window, hangs on authorize, or never connects is almost always OAuth, popups, cookies, or the wrong endpoint URL. The checks that fix it.
The symptom
You click Create or Connect to add a custom MCP server in ChatGPT and get a blank page, a spinner that never resolves, or an authorization window that closes without connecting. The connector was never saved, so there is nothing to toggle in a chat. The cause is almost always the URL, the browser, or the server's OAuth setup, not ChatGPT itself.
Check 1: the URL points at the MCP endpoint
A connector pointed at https://example.com instead of https://example.com/mcp fails the handshake even though the homepage returns 200. ChatGPT often surfaces that as a blank or stalled add rather than a clear error. Use the exact endpoint path from the server's documentation before changing anything else.
Check 2: popups and third-party cookies are allowed
The authorization step opens a separate window. If it renders blank or flashes and closes, a blocked popup, an ad blocker, or disabled third-party cookies is the usual cause. Allow popups and cookies for chatgpt.com and for the server's own domain, pause blocking extensions, and retry. In a private or hardened browser profile, try a normal window.
Check 3: the server actually serves OAuth
Remote MCP connectors expect the server to advertise OAuth: authorization-server metadata and dynamic client registration, or a documented bearer token. If the server answers the base URL but never returns that metadata, the authorize screen has nowhere to go and stays blank. Run the endpoint through the MCP config validator to see whether the handshake and OAuth discovery succeed from outside ChatGPT.
Check 4: add it on the web, not the app
Custom MCP apps are created and managed on the web, so complete the add at chatgpt.com in a normal browser window first. OpenAI's help docs describe MCP apps as web-first: the desktop and mobile apps pick up the connection after it is linked on the web rather than being where you add it. If the embedded window in the desktop app hangs on a blank screen, finish the authorization in the browser instead.
Check 5: rule out the plan and Developer-mode gate
If the problem is that the Create button is missing entirely, this is not a connect failure at all. See no MCP servers or Connectors option in settings to confirm your plan and Developer mode first. A hosted server such as Hjarni removes most of this surface: one https endpoint, standard OAuth, no local process, no port, and no token file to paste.
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