Requests cannot be released during the upgrade
Message no. TR811
An upgrade to a new version is currently running in your SAP ystem. No change requests or transports are released in the current upgrade phase.
Request SIDK900123 is not released.
Wait for the upgrade to finish. You can then release request SIDK900123.
Further information can be found in the upgrade guide.
Note in particular the section about adjusting the ABAP Dictionary objects.
Follow Note: 1901463