Message
Executed as user: COV\yyV_IPMPS13SQLAdmin. Microsoft (R) SQL Server Execute Package Utility Version 11.0.5058.0 for 64-bit Copyright (C) Microsoft Corporation. All rights reserved. Started: 6:18:40 PM Error: 2016-02-11 18:18:40.98 Code: 0xC0024104 Source: {B1B5759C-3645-4296-9513-AAA09ED447AA} Description: The Execute method on the task returned error code 0x80131621 (Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.). The Execute method must succeed, and indicate the result using an "out" parameter. End Error Warning: 2016-02-11 18:18:40.98 Code: 0x80019002 Source: OnPreExecute Description: SSIS Warning Code DTS_W_MAXIMUMERRORCOUNTREACHED. The Execution method succeeded, but the number of errors raised (2) reached the maximum allowed (1); resulting in failure. This occurs when the number of errors reaches the number specified in MaximumErrorCount. Change the MaximumErrorCount or fix the errors. End Warning Warning: 2016-02-11 18:18:40.98 Code: 0x80019002 Source: Subplan_1 Description: SSIS Warning Code DTS_W_MAXIMUMERRORCOUNTREACHED. The Execution method succeeded, but the number of errors raised (1) reached the maximum allowed (1); resulting in failure. This occurs when the number of errors reaches the number specified in MaximumErrorCount. Change the MaximumErrorCount or fix the errors. End Warning Error: 2016-02-11 18:18:42.09 Code: 0xC0024104 Source: Back Up Database Task Description: The Execute method on the task returned error code 0x80131621 (Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.). The Execute method must succeed, and indicate the result using an "out" parameter. End Error Error: 2016-02-11 18:18:42.11 Code: 0xC0024104 Source: {4612ABAD-E377-4987-926D-93BE18CF554A} Description: The Execute method on the task returned error code 0x80131501 (An exception occurred while executing a Transact-SQL statement or batch.). The Execute method must succeed, and indicate the result using an "out" parameter. End Error Warning: 2016-02-11 18:18:42.11 Code: 0x80019002 Source: OnPostExecute Description: SSIS Warning Code DTS_W_MAXIMUMERRORCOUNTREACHED. The Execution method succeeded, but the number of errors raised (2) reached the maximum allowed (1); resulting in failure. This occurs when the number of errors reaches the number specified in MaximumErrorCount. Change the MaximumErrorCount or fix the errors. End Warning DTExec: The package execution returned DTSER_FAILURE (1). Started: 6:18:40 PM Finished: 6:18:42 PM Elapsed: 1.875 seconds. The package execution failed. The step failed.
Please enable package logging and if you are using SQL Server Agent to schedule it; make sure you run it as CmdExec step type. That should give some clues about what cause of the problem
Please take a look on this it may be helpful SSIS package does not run when called from a job step - SQL Server | Microsoft Learn
I don't know what (SQL Tool) generated this output, but its no help at all, is it? 
It seems to be saying "There was an error, only one error is allowed, you can raise the Max Error Count if you like" - useless ...
In addition to fixing that, if it was a backup that you were attempting to run, then there may be a useful error message in the SQL Errors Log ( you can see that in SSMS : Management - SQL Server Logs)
If there is something like Disk Full then that will show up there.
DTEXEC produces this type of output.
Have you enabled logging in your package? If not, do so and rerun and see what the log says
Thanks. Couldn't they have come up with something better for debugging? I note that your advice is to turn on logging, which probably does just that job, but if you don't do that and then suddenly it breaks (months after putting into production) presumably you have zero information to gdo on without rerunning it? (which might be a very undesirable action!)
No doubt there is a good reason to have logging off by default ...
The usual reason is that it can produce a lot of output. I see that it is on by default for SSISDB jobs.
Thanks guys for your opinion . I am using Sql server management tool . I have created a maintenance plan which take the backup of All database . when I try to run , It throws the above error but if i take backup using T-sql its working fine . Its strange !!
Folk here don't generally have a very high opinion of Maintenance Plans built into SSMS (although not because they produce errors!)
If you are just looking for an easy-to-set-up, reliable-to-run, database backup tool you might want to have a look an Minion Backup. Its pretty much Install and Forget - configuration is very easy, but it has stuff you adjust if you need to.
Instead of using the job history - you need to use the maintenance plan history. Open the folder for maintenance plans and right-click on the plan that is failing. View history from here...
This will give you a line item for each task in your plan - and you should be able to narrow down which task is failing. On that task the history will display the actual error you are getting...