Message type: E = Error
Message class:  CNV_OM_PS2 - Preselection 2 
Message number: 001
Message text: Unable to get task instance for task GUID &1
Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.
To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.
Unfortunately, there isn't any extra information in this error notice.
First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).
Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.
You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.
The SAP error message CNV_OM_PS2001: Unable to get task instance for task GUID &1 typically occurs in the context of SAP data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or other tools related to data transfer.
Cause: This error can arise due to several reasons, including: Invalid Task GUID: The task GUID provided may not exist or may have been deleted. Database Issues: There may be issues with the database connection or the underlying database tables that store task instances. Authorization Issues: The user executing the task may not have the necessary authorizations to access the task instance. Inconsistent Data: There may be inconsistencies in the data or configuration that prevent the system from retrieving the task instance. System Configuration: The system may not be properly configured for the migration or conversion process.
Solution: To resolve the error, you can try the following steps: Check Task GUID: Verify that the task GUID you are using
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_OM_PRESEL304 Unexpected error when scheduling preselection tasks.
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_OM_PRESEL303 Communication failure: &1
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_OM_PS2010 GUID &1 does not describe a data model
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV_OR_ANA2000 &1&2&3&4
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.