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 v2.1.321,
ImprovementsSection of the release
What
An MCP server is an outside program, often called a connector, that gives Claude Code extra tools. Claude Code now declines to upload files to a server when either applies:
The server uses a protocol version older than MCP 2026-07-28
The server's file-uploads entry has no upload section
Claude Code also logs the server's file-uploads entry.
Why
If files are not reaching a connector, this may be why: the server has to use the newer protocol and say that it accepts uploads.
