Troubleshooting

Address already in use

Another process is listening on the selected port. If it is an existing pyplotdesigner instance, open http://127.0.0.1:8080/ui or stop it with Ctrl+C in its terminal. You can also choose another port:

python -m pyplotdesigner.gui.main --port 8081

Browser does not open

Open http://127.0.0.1:8080/ui manually, substituting your chosen port. To run without automatically opening a browser:

python -m pyplotdesigner.gui.main --no-browser

Changing a constant fails

get_constant(name) returns None if the constant does not exist. Use its exact name from the GUI. Editing an axis property directly can have no lasting effect if a constraint controls it; edit that constraint’s constant.

The layout stops updating

Check that the Python server is running. Circular or incompatible constraints can prevent solving; remove the conflicting relationship. Import-format errors appear in a dialog; export failures appear in the status bar.