SAP Note 17171 - Execute report group: error GR205

Symptom:

A report group is executed. Selection terminates with error message GR205:
Internal error: entry in COLUMNS does not exist (MERGE-RC)

Cause and prerequisites

Program error

Solution
The error has not been localized yet, however, the following workaround is available:
If the report has a multi set in the column that contains a data set, please position the data set as the last item.