Unable to start execution of step 1 (reason: line(1): Syntax error)

You may receive the error “Unable to start execution of step 1 (reason: line(1): Syntax error” under below circumstances in SQL Server 2005/2008.
1. Created a new maintenance plan
2. Modified the path in existing maintenance plan
3. Existing database fails due after File servers IP Change..etc

Here is the complete error message:
Execution failed. See the maintenance plan and SQL Server Agent job history logs for details:
Additional Information:
Job ‘ Log_Backup’ failed. (SqlManagerUI)

Additional information from Log File Viewer:-
Executing the query "EXECUTE master.dbo.xp_create_subdir N'\\\\backup\\t..." failed with the following error:"Cannot open backup device \\backup\testdb.trn'. Operating system error 53(The network path was not found.). BACKUP LOG is terminating abnormally.” Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly.

Solution:
1. Check the login used to schedule the backup has access to backup device path and read/write permissions.

Run below t-sql from New Query to check the permission.
EXECUTE master.dbo.xp_create_subdir N'\\backup \testdb'

2. If your Backup Maintenance plan suddenly stopped working after Network maintenance then it may be related to name resolution to File Server Name or IP Change or Alias name that you are using in the backup.

Check whether you are able to resolve correct name, IP address using nslookup or check with your Windows team to fix name resolution.
For ex:- nslookup "server name or IP address or File server name"

3. If you still have issues
- Go to SQL Server Agent\Jobs and click properties
- Go to Steps section
- Highlight the Sub plan and click Edit
- In the “ package section” add a Backslash to the beginning of the path listed

Regards
Satishbabu Gunukula
http://www.sqlserver-expert.com