Argument data type text is invalid for argument 1 of len function. code example

Example: Argument data type text is invalid for argument 1 of len function.

If you try to use len() on a Text field, you will get an error Argument data type text is invalid for argument 1 of len function.

The answer to this is the Datalength() function which will return the length of any expression. This can be used on all data types including text, ntext, image and varbinary.