Zero matches is misleading when the true problem is that a search parameter is incorrect. I expect to be told that my regular expression is not correct, and other search activities to be aborted.

Observe that none report on the invalidity of the regular expression, but rather indicate zero matches. Try other search actions (besides Find Next) that support regular expressions without changing the Find what box data.

The status bar at this point should indicate that the regular expression is invalid. Observe the Find window's status bar indicates in blue: Count: 0 matches. (This is correct and desired behavior and is only shown here to contrast with the following incorrect behavior.) Observe the Find window's status bar indicates in red: Find: Invalid regular expression.

Select Regular expression for the Search mode.

(Obviously this applies only when the user sets the Search mode to Regular expression.) Steps to Reproduce the Issue An invalid-regular-expression message needs to be shown on the Find window's status bar whenever ANY type of find/replace/count/mark operation is initiated and the user's regular expression is malformed.

The error message Find: Invalid regular expression is used to alert the user to a syntax problem with their regular expression ONLY when a Find Next action is invoked.

Notepad++ regular expression search