10000213 
Message
Transaction no. [transaction number] was already reversed
Diagnosis
You have opened the Journal Entry window and have tried to reverse a journal entry by changing the reverse date and choosing the Update button. However, the journal entry was previously reversed as follows:
In the Journal Entry window, you have selected the Reverse checkbox and you have defined a reverse date.
The reverse date has passed.
You have opened the Reverse Transactions window, selected the journal entry, and have chosen the Reverse button. SAP Business One has reversed the journal entry.
You cannot reverse the same journal entry twice.