Hi Alan, this is documented at https://docs.python.org/3/reference/compound_stmts.html#the-try-statement:


> When an exception has been assigned using as target, it is cleared at the end of the except clause. This is as if
>
> except E as N:
>    foo
>
> was translated to
>
> except E as N:
>    try:
>        foo
>    finally:
>        del N
>

This is because the exception keeps a reference to the code frame that would make a cycle with the locals which would not be destroyed until the next garbage collection.

I think you will need to use a different name in the except clause.