Specify search string only in FROM field

What causes this issue?

You have entered a value in the field 'TO' for the 'String search'
funtion.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

For the 'String search' function, enter the string which you are
searching for in the 'FROM' field and leave the 'TO' field blank.

Error message extract from SAP system. Copyright SAP SE.