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SAP Performance 101: The back-end sessions terminated

A few weeks ago one of my customers have an issue with an SAP ERP system running on SLES 12 + SAP HANA 1.22. The dammed error message “back-end session terminated” appeard which usually means having fun checking really inside of the SAP system. I think this case is quite interesting because the solution was completely different to what we though in the beginning. It also taught me a quite valuable lesson 🙂

The problem

The customer performed a system refresh from PRD to QAS in a SAP ERP system. After finishing the system refresh there was an issue when executing some transactions. For example, if I executed the XDN1 transaction we got the following error message:

SID: SAP System Message: Work process restarted; back-end session terminated

This error message appeared as a pop-up when executing the transaction, closing the current SAPGUI window. The same issues appeared on different situations like using the technical help, generating profiles with PFGC transaction or using VA01 transaction.

The investigation

First thing I did was checking the work process trace. The reason is because each time a work process dies or when we get the error message “back-end session terminated” the reason is written in the WP trace. Even if you don’t understand the trace file the reason is still there so you can look for a solution considering this information. In this case when the WP died there was the following messages:

Information in the WP trace
Information in the WP trace

The first part is a warning related to an insufficient value of the vm.max_map_count. I checked the OS and the parameter vm.max_map_count wasn’t even defined in the /etc/sysctl.conf file as SAP recommends when installing on SLES. I added the parameter and rebooted the system, unfortunately it didn’t work.

The second part is the error message itself. It just says that the session has been deleted with the error ERROR-CORE-PROCESS_CRASHED. This could be caused by different reasons. For example, if the roll area is insufficient then the user’s session in the WP will die. Unfortunately this wasn’t the case, the system had enough memory in all the areas for executing the transaction.

Next thing to check was the SQL queries being executed in the system while executing the XDN1 transaction. I got the SQL queries doing a performance trace in the SAP system and then I executed the queries directly in the HANA database. Everything worked correctly so the problem was not related to the database.

I had no clue for solving the issue so I decided to contact the SAP Support. They provided the following notes so I had to check if any of them solved the issue:

The solution

Finally SAP solved the issue performing the following steps:

  1. Start transaction SE41
  2. Enter “SAPLSHL2” for field “Program”
  3. Enter “F1HELP” for field “Status”
  4. Select from menu: “User Interface” → “Activate”

These steps solved all the issues we had with different transactions and the technical help. It is quite interesting because I’m still trying to figure what happened after the system refresh that could cause these errors. We performed the same system refresh procedure dozens of times in the system and we never had this issues.

In case you have these kind of issue in the future I would recommend checking the following:

  • The work process trace file. You can get them directly in the OS or using ST11 transaction.
  • OS trace files such as Windows event monitor or /var/log/messages in Linux OS.
  • Memory parameters on both OS and SAP instances.
  • SQL queries being executed while using the transaction. Check those queries directly in the database if you can.

If nothing of that helped then open a support message to SAP Support and start praying to the Basis Gods.

Conclusions

Two ideas I want to share with you about this case:

  • Sometimes thinking “out of the box” helps a lot for finding the origin of the problems. If you tried everything and it didn’t work try changing the approach
  • Being honest I would never guess how to fix this issue without the help of SAP Support. Sometimes a cry for help is better than be stuck in the same problem over and over.

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