There is info on this in note: 362883
"There are too many entries in the first level of the user menu. Usually, 300 nodes are displayed on the first menu level as default. The last node displayed is the entry "Display more nodes on this level". When you click on this node, the remaining nodes are loaded on the front end. If you do this before opening the first folder, the error described above does not occur."
The solution is in the note
