Find the server output
The server writes diagnostic messages to the output of your MCP client. The messages stay on your computer.
In VS Code:
- Open the Command Palette.
- Run MCP: List Servers.
- Select the DAX Lib MCP server.
- Select Show Output.
In the Code tab of the Claude application or in Claude Code, run /mcp to see the status of the server. If the server is not in the list, make sure that the entry is at the top level of %USERPROFILE%\.claude.json, then restart the application.
In the Chat tab of the Claude application, the MCP logs are in %APPDATA%\Claude\logs. The file mcp-server-daxlib-mcp.log contains the output of the server, if the server name in the configuration is daxlib-mcp.
In Cursor, open the Output panel and select MCP Logs.
Do the failed action again, then read the most recent messages.
To collect a detailed diagnostic trace, refer to Troubleshooting DAX Lib MCP in the daxlib-mcp repository.
The server does not start
| Problem | Solution |
|---|---|
The message says that the platform package @daxlib/mcp-<platform>-<arch> is not installed. |
The server runs only on Windows x64. On a supported platform, run npm install @daxlib/mcp-win32-x64, then try again. |
npx is not found. |
Install Node.js version 18 or higher. Restart the MCP client after the installation. |
The message mentions npx or spawn. |
Use cmd as the command, with the arguments /c, npx, -y, @daxlib/mcp, and --start. On Windows, npx is a .cmd script, and some clients cannot start it without a shell. |
| The server is not shown in the client. | Make sure that the JSON configuration is correct. Make sure that you use the correct key (mcpServers or servers) for your client. Restart the client. |
To test the server outside the client, run npx -y @daxlib/mcp --version in a terminal.
Search and package errors
| Message | Cause and solution |
|---|---|
| No packages matched the query. | The query is matched as one substring. Use one keyword, for example svg, date, or format. If you excluded prereleases, include them. |
| No DAX Lib package with this id exists. | The package id is not correct. The message can show possible matches. Use search_packages to find the correct id. |
| The package does not have this version. | The message shows the available versions. Use one of them. |
| The package version does not have a README. | The author did not publish a README for this version. |
Installation errors
| Message | Cause and solution |
|---|---|
The dataSource does not match any local Power BI Desktop instance. |
The instance is closed, or the value is not correct. Ask the assistant to list the open instances again, then select one. |
| The connection to the instance could not be established. | Make sure that Power BI Desktop is open and that the model is loaded. Try again. |
| The model’s compatibility level is lower than 1702. | User-defined functions need compatibility level 1702 or higher. The DAX Lib MCP server does not change the compatibility level. Raise it yourself, then install the package again. Refer to Raise the compatibility level. |
| The instance hosts a number of databases different from one. | The model is not loaded. Open the target model in Power BI Desktop, then try again. |
| The package could not be read. | The package content is not valid. Do not try again. Report the problem to the package author. |
| The engine could not save the change. | Power BI Desktop rejected the change. Read the error message. Do not try again automatically. |
Raise the compatibility level
You can use the Power BI Authoring MCP server (GitHub repository) to raise the compatibility level to 1702 or higher. Suggested prompt:
Connect to the model open in Power BI Desktop and make sure that the compatibility level is at least 1702.
The installed functions are not saved
The server changes the model in Power BI Desktop, but it does not save the file. Save the file in Power BI Desktop.
Report a problem
To report a problem with the MCP server, open an issue on GitHub. Include the server version (npx -y @daxlib/mcp --version), your MCP client, and the messages from the server output.