The message shown by the error looks like this:

How might you run into the error?

While Flutter’s widgets are generally flexible in how they can be composed
together in a UI, a small subset of those widgets expect specific parent
widgets. When this expectation can’t be satisfied in your widget tree, you’re
likely to see this error.

Here is an incomplete list of widgets that expect specific parent widgets
within the Flutter framework. Feel free to submit a PR (using the doc icon in
the top right corner of the page) to expand this list.

Flexible

Row, Column, or Flex

Expanded (a specialized Flexible)

Row, Column, or Flex

Positioned

Stack

TableCell

Table

How to fix it?

The fix should be obvious once you know which parent widget is missing.