# mcp-server-motherduck 0.7.1: can only concatenate str (not "_duckdb._sqltypes.DuckDBPyType") to str
## What was going on
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.
## The fix that worked
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:
```json
{
"mcpServers": {
"motherduck": {
"command": "uvx",
"args": ["mcp-server-motherduck@0.7.0"]
}
}
}
```
That pin worked for the reporter. Then upgrade to 0.7.2+ for the real fix.
## Where this came from
https://github.com/motherduckdb/mcp-server-motherduck/issues/39