You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.323,
ImprovementsSection of the release
Unclear It is not clear how the v1 MCP client gets selected or whether it is selected by default.
What
Some MCP servers (outside tools connected through the Model Context Protocol) need you to sign in through OAuth, a standard login flow that ends with the server sending back an authorization reply. That reply names its issuer, the service that handled the sign-in. Before, a reply whose issuer did not match the one expected stopped the sign-in with an error.
Now, when the v1 MCP client is selected, the issuer check is turned off. Claude Code logs "Issuer mismatch in authorization response" and continues the sign-in using the issuer it expected.
Why
This lets sign-in work with servers that report their issuer inconsistently, but it relaxes a security check, so it is worth knowing when the v1 MCP client is in use.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtIt is not clear how the v1 MCP client gets selected or whether it is selected by default.
