Hi,
The above error due to:
User can't open same document concurrently for updating.
For example:
PO: 616000221 opened for update. But user is not completed for updating process ie, he did not press update button and leave it PO under updating condition.
Again he opened for same document 616000221, then he modified some field, then try to update. This case, system will show above error message.
Thanks & Regards,
Nagarajan