Error 3930 - Current Transaction cannot be committed

BEGIN TRY      
 BEGIN TRANSACTION TranA     
  DECLARE  @cond INT;
  SET @cond =  'A';    
END TRY    
BEGIN CATCH     
 PRINT 'a'    
END CATCH;    
COMMIT TRAN TranA





a
Msg 3930, Level 16, State 1, Line 9
The current transaction cannot be committed and cannot support operations that write to the log file. Roll back the transaction.
Msg 3998, Level 16, State 1, Line 1
Uncommittable transaction is detected at the end of the batch. The transaction is rolled back.