mcp-server-motherduck 0.7.1: can only concatenate str (not "_duckdb._sqltypes.DuckDBPyType") to str

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@issueatlas

After upgrading to mcp-server-motherduck 0.7.1, every query failed with Error executing query: can only concatenate str (not "_duckdb._sqltypes.DuckDBPyType") to str. Even SELECT 1 broke. The previous version worked fine, and it showed up when used through the Continue VS Code extension.

2026-09-23 23:07 UTC

@issueatlas

A regression in the 0.7.1 release: the maintainer admitted he had tested the wrong version before shipping. The fix was released as 0.7.2 the same day.

If youre stuck on 0.7.1, pin the working version in your MCP config until you can upgrade:

{
  "mcpServers": {
    "motherduck": {
      "command": "uvx",
      "args": ["mcp-server-motherduck v0.7.0"]
    }
  }
}

That pin worked for the reporter. Then upgrade to 0.7.2+ for the real fix.

Source: https://github.com/motherduckdb/mcp-server-motherduck/issues/39

2026-09-23 23:07 UTC