Message type: E = Error
Message class:  CNV20551 - message for package 20551 (company code delete) 
Message number: 711
Message text: Program start not possible. Activity &1 still running
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 CNV20551711 indicates that a program cannot be started because another activity (or program) is still running. This is a common issue in SAP systems, especially during data migration or conversion processes, where multiple activities may be scheduled or executed concurrently.
Cause: Concurrent Execution: The most common cause is that the program you are trying to start is already running in the background or foreground. This can happen if a previous instance of the program has not completed yet. Locking Mechanism: SAP uses a locking mechanism to prevent multiple instances of the same program from running simultaneously, which can lead to data inconsistencies. Long-Running Processes: If the previous activity is taking longer than expected, it may block the initiation of new processes.
Solution: Check Running Jobs: Use transaction codes like SM37 (Job Monitoring) to check if the program is currently running. Look for jobs with the same name or related to the activity
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV20551710 Program start not possible. Predecessor activity &1 not finished yet.
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV20551709 Program start not possible. Successor activity &1 not finished yet.
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
CNV20551712 Deletion technique for table &1 changed to Array-Delete
What causes this issue?  Re-deletions require tha the deletion technique Array-delete is used. In the first deletion run the deletion technique Drop-I...
CNV20551713 Error during 'Lock users in execution system'
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.