The Invalid Expression error is issued in the following situations:

Fix the expression that has this division by 0.

Fix this Text literal in your expression.

Check the Scope tree of your expression and select the desired element from there.

Check your expression to validate its operands, operators, and variables.

Check the Built-in function or the User Function definition, to validate which input parameters are mandatory.

Check the Built-in function or the User Function definition to validate its arguments and the  function calls syntax.

Replace some of the function calls by variables where their value has been previously assigned invoking the necessary function, in the action flow.

Check the Built-in function or the User Function definition, to validate its arguments or; in case you've actually deleted a parameter,  fix the expression errors.

Check whether you're using the same name more than once or if you'd already mapped the argument by position and then used its name again, in the function call.

Change the function to use a parameter from outside the aggregate.

 

Clicking the symbol will take you directly to the invalid expression.

See Also

About Expressions | Fix Expression Errors | Built-in Functions | User Functions | About Error Messages