I believe runtime error 16 is "maximum string size exceeded". The message text should include information as to the name of the object, event/function name, and line where this error occurred.
You need to examine the code at and prior to where the error occurred to determine why this happened. For example, you may be concatenating to a string inside of a loop that does not terminate properly. We really have no way to determine the root cause of the error in your application.
Best regards, John