Python Debug Server / Flask / FastAPI run configurations missing in IntelliJ IDEA

Problem

In IntelliJ IDEA with the Python plugin, the Python Debug Server, Flask, and FastAPI run configurations are unavailable. Existing configurations show as "unknown", and the types are missing from the list when adding a new configuration with the + button. This started in IntelliJ IDEA 2025.3 and also affects 2026.1 and later.

Cause

Starting with 2025.3, the Python debugger moved to a Debug Adapter Protocol (DAP) backend based on debugpy, and these run configurations are now provided by the Python DAP Debugger plugin. The plugin is bundled in PyCharm but not in IntelliJ IDEA, so the configuration types do not appear until it is installed.

Resolution

To resolve the issue, ensure the Python DAP Debugger plugin is installed by following these steps:

1. Navigate to File | Settings | Plugins.
2. Search for Python DAP Debugger in the marketplace.
3. Install the plugin.
4. Restart IntelliJ IDEA.

After the restart, the Python Debug Server, Flask, and FastAPI configurations appear under Run | Edit Configurations when clicking the + button.