Unclear error for incorrect path with parallel index creation
If you are creating indexes using the parallel index creation protocol,
and there is an incorrect path specification for an index that is not the
first one in the list of indexes to be created, the error message does
not provide useful information for tracking down the actual cause of the
The errors may be "Illegal attempt to execute a protected method" or "Attempt
to insert a key into the B-tree that was an invalid class for which the
B-tree was created".