Hi Ondrej,
Looks like the error is not fully from SBO.
1. Action update OITM record has been failed! Update item card has been failed!
2. Error: -1 Error in ´ItemsService´ during command ´Update´
The first part is from the Addon
The 2nd part is from SBO.
In my case it happens with my UDO.
The last time I saw this error from SBO is when I open up two UDO forms on the same record at the same time.
On the first form I did an Update.
On the 2nd form, My addon process a calculation and tried to update the form via UI (click button 1).
This error is more like the standard error 'Another user modified record'
Check if you have the same problem.
Regards
Edy