I get ORA-13605 when trying to run SQL Tuning Advisor from SQL Developer
The solution is very simple. The string of the query is just too long. 

I'm trying to optimize a stored procedure using dynamic sql with a parameter to decide if the sql is executed or output.

I just copied the output into a fresh sql developer pane and tried to use the tuning advisor.

The problem is that the generated output has a lot of trailing blanks, I just have to remove them.