The job failed. The Job was invoked by Schedule 1012
Since you indicated your 'transaction log' backup maintenance plan had been working, but was now failing, double check to make sure none of the databases involved in the maintenance plan have somehow gotten changed to SIMPLE recovery - transaction logs cannot be backed up in SIMPLE recovery mode.

Run this query to identify the recovery mode of all of your databaes.

select name,recovery_model_desc from sys.databases

To begin taking transaction log backups again, you'll need to re-establish the log chain by taking at least a DIFFERENTIAL backup (although, to keep things nice and clean, I'd recommend a new FULL backup) to bridge the gap between the time the database was changed to SIMPLE and now.

For more information about the transaction log and SIMPLE recovery, please check out these links:

Backup Under the Simple Recovery Model

Transaction Log Truncation