Have you checked closed issues? https://github.com/Textualize/textual/issues?q=is%3Aissue+is%3Aclosed

Yes, no issue mentioned problems with MaskedInput validation.

Have you checked against the most recent version of Textual? https://pypi.org/search/?q=textual

Yes

Please give a brief but clear explanation of the issue. If you can, include a complete working example that demonstrates the bug. Check it can run without modifications.

1. Run the app

uv run --script masked_input_value_error.py

2. Press the key e or any other non digit.
3. Watch the app crash with a ValueError.

masked_input_value_error.py

# /// script
# requires-python = ">=3.13"
# dependencies = [
#     "textual==1.0.0",
# ]
# ///
from textual.app import App, ComposeResult
from textual.widgets import MaskedInput


class BugApp(App[None]):
    def compose(self) -> ComposeResult:
        yield MaskedInput("9", "9")


app = BugApp()
app.run()

It will be helpful if you run the following command and paste the results:

textual diagnose

If you don't have the textual command on your path, you may have forgotten to install the textual-dev package.

Feel free to add screenshots and / or videos. These can be very helpful!

Textual Diagnostics

Versions

Python

Operating System

Terminal

Rich Console options