An Excel validation rule can warn someone who types an unacceptable value while still allowing invalid data to arrive through copying or other operations. A dropdown list is therefore not proof that every existing record follows the rule.

This guide uses desktop Excel for Windows. Preserve a copy of the workbook before cleaning a pasted import. Identify the expected rule first: for example, a quantity must be a whole number within the allowed range, or a status must come from a particular list.

Inspect the existing values against the rule

On the Data tab, open the Data Validation menu and choose Circle Invalid Data. Excel marks cells whose existing values do not meet their validation criteria. Microsoft documents copying, filling, formulas and macros as ways invalid values can enter despite validation messages.

Inspect a marked cell’s value and its validation settings before changing it. The value may be wrong, but an outdated rule can also reject a legitimate new category. Confirm the intended policy with the person responsible for the list rather than inventing a replacement.

Clear Validation Circles removes the visible markings. It does not correct the values, so use that command only when you deliberately want to hide the indicators.

Correct the cause and recheck the import

For a small correction, compare the record with the source and fix the value deliberately. For many marked records, look for a shared import issue, such as the wrong column mapping or an unexpected category spelling, before making bulk substitutions.

Run the invalid-data check again after the changes. Check several unmarked records too, including one near the beginning and end of the pasted range. A value can satisfy a broad rule while still belonging to the wrong record.

Keep a short note of the accepted rule and any source correction. If this is a recurring import, include the post-paste validation check in the handover procedure instead of relying solely on the warning shown during manual typing.

References: Microsoft: displaying invalid-data circles.