QlikView Task Failing with System.ArgumentNullException: Value cannot be null

[Yoichi_Hirotake]

Value cannot be null is a generic error that can have multiple root causes. 

The Distribution or Task reload fail with:

System.ArgumentNullException: System.ArgumentNullException: Value cannot be null.

Environment:

QlikView 

Resolution:

1. Verify that the supported .net framework version is installed and that no duplicates are available. It may be necessary to reinstall .net framework.
2. QlikView could not retrieve the correct parameter when the task requires it. This could be caused by an overloaded system.
3. The QlikView server is currently down due to a crash or maintenance window.
4. If two tasks require identical access to documents or external sources, ensure they are not started at the same time. 
5. Verify that the service account is a local administrator and has the correct permissions. See QlikView Service Account Requirements

[john_oll]

System.ArgumentNullException: System.ArgumentNullException: Value cannot be null
also happens if in the

C:\ProgramData\qliktech\DistributionService\Tasks\Task_*.xml
file(s)
it links to a qvw that is not accessible. 

(e.g. if you copy the folder during a QlikView server migration, and forget to change the old server name in all those xml files to the new server name (change is easy to do with Notepad++) )