Community
Enterprise Resource Planning Blog Posts by SAP
cancel
Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for 
Search instead for 
Did you mean: 
Read only

VCH AFL – Installation, Upgrade, Troubleshooting

florian_soe
Product and Topic Expert
Product and Topic Expert
‎2024 Nov 19 12:25 PM
7,925

General

The Application Function Library (VCH AFL) is fundamental to Advanced Variant Configuration (AVC). It's written in C++ and is technically a plug-in running on the SAP HANA DB script server. The VCH AFL evaluates all object dependencies in a configuration model with processing mode "Advanced." This concerns all dependencies not attached to bill of material items (BOM items), also referred to as "high-level dependencies."

The VCH AVC lifecycle is managed by SAP in S/4HANA Cloud Public Edition, so the following information applies only to S/4HANA (on-premise) and S/4HANA Cloud Private Edition. Here, customers have to manage installation and upgrades themselves.

 

Installation

The VCH AFL can be downloaded from the software center (https://me.sap.com/softwarecenter). Search for the VCH AFL in Software Downloads and add the S/4HANA version, e.g., "VCH AFL 2023". After that, filter for the appropriate SAP HANA DB version (= SAP HANA revision), e.g., 79.01.

Search_for_VCH_AFL_2023.png

search_for_hana_revision_79.01.png

Please note that the patch level of the VCH AFL does not relate to the patch level of SAP HANA: VCH AFL with patch level 2 and SAP HANA patch level 0 work perfectly fine together. However, you should always take the highest patch level available. A general AFL note explaining the versioning can be found here: https://me.sap.com/notes/1898497/E. How to install the VCH AFL and which post-installation steps are necessary are described in the S/4HANA installation guide. You can find this guide on the main page of the help portal (https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE). Scroll down to the section "Implement," subsection "Guides":

Implement_Guides.png

The Installation Guide points to the SAP HANA Server Installation and Update Guide: https://help.sap.com/docs/SAP_HANA_PLATFORM/2c1988d620e04368aa4103bf26f17727/7eb0167eb35e4e288541520.... The following note describes the manual installation of the VCH AFL: https://me.sap.com/notes/2987015 (S/4 Release 1909OP and following).

 

Update

When using the AVC, please always keep SAP HANA DB and VCH AFL up to date, as explained here: https://me.sap.com/notes/3318944. Bug fixes and performance improvements are usually only available with the latest revisions of the AFL. When you update the SAP HANA revision, first uninstall the old VCH AFL, then update SAP HANA, and then install the new VCH AFL. Check section no. 7 ("Updating the SAP HANA System") in the SAP HANA Server Installation and Update Guide for further additional components that might need a simultaneous update in your current setup.

When upgrading the SAP HANA DB, you can look for the latest VCH AFL patches in the software center. The SAP HANA DB installer does not always contain the latest VCH AFL.

 

Configuration

You can also manually configure some parameters of the VCH AFL concerning memory allocation or deletion of expired sessions. For details, refer to this note: https://me.sap.com/notes/2551305/E.

 

Dos and Don'ts and Troubleshooting

Run report VCH_HL_AFL_CHECK in transaction SA38 to check whether VCH AFL is installed correctly. If an error occurs, scroll down to see the error message. If the report results in errors but you are sure to have followed the installation guide, check whether one of the scenarios described below applies. If not, please create a ticket on component LO-VCH-ENG-AFL.

  • For SAP HANA revisions up to 59.14 or up to 79.01 (depending on the code line), the following issue exists: If you restart the index server of the DB while the script server is still running, the VCH AFL stops working. You can see how long the servers have been running in the transaction DBACOCKPIT under Configuration Services. If the script server is older than the index server, restart it. See also https://me.sap.com/notes/3511162. 
  • In S/4HANA releases up to 2021, the temporary tables used for communicating between the VCH AFL and AS ABAP (ABAP application server) can accumulate, resulting in significant memory consumption. Please see https://me.sap.com/notes/3218076/E for how to fix this.
  • When running S/4 2022 FPS 0, please apply note https://me.sap.com/notes/0003247490 to get the VCH AFL to work (this is also mentioned in the release notes).
  • When you run S/4 2025, a bug in the VCH_HL_AFL_CHECK report may occur: an error message stating that the "AVC call behaved wrongly" appears, despite AVC being installed correctly. In this situation, please apply the note https://me.sap.com/notes/3644298.
  • If an error message from VCH_HL_AFL_CHECK persists, drop all the temporary tables used for communication between VCH AFL and AS ABAP. To find these temporary tables, first look up the name of the database schema in SapLogon --> System --> Status. Then enter transaction code DBACOCKPIT --> Diagnostics --> Tables + Views. Enter the above schema name and search for tables with the pattern "VCH*GEC*". Note down the table names that start with VCH_<S/4 Release year> (or with VCH_AREA ). Go to transaction code DBACOCKPIT --> Diagnostics --> SQL Editor and execute this statement: DROP TABLE "<schema name>"."<table name>";( You should first do this with tables ending on "_OCDR", and re-test,  then with those having "GEN_IN" in the middle, and re-test.)

 

Further SAP Notes