I have lost an hour today trying to find a bug in my SSIS package, and it was so small - just two letters - "GO"

I had an Execute SQL Task with an input parameter and I had an SQLStatement with some lengthy logc and a "GO" at the end.

Every time I tried to execute it I got an error message "[Execute SQL Task] Error: Executing the query "
" failed with the following error: "The variable name '@StartFrom' has already been declared. Variable names must be unique within a query batch or stored procedure."

I got desperate trying to find where am I declaring the @StartFrom. I even removed it completely from script and still got this error. Eventually, gloomily poring over my script I saw a "GO" statement and decided that maybe he is the culprit - causing Execute SQL Task to declare the Input Parameter twice, and I was right. That is exactly what happens.

When Execute SQL Task sees GO, it redeclares the variable specified in the Parameter Mapping, and then himself not liking it complains about it being declared twice. Isn't that just ingenious?