Symptoms

Upgrade of the Avamar Windows client fails with the error: Upgrade verification failed. Try to run the installer again. Figure 1: Visualization of the Error The same upgrade succeeds on other clients, indicating the issue affects only one specific system.The problem typically occurs after an incomplete or unclean uninstall of a previous Avamar client or plug-in.Attempts to uninstall the old client using msiexec /x return: The software you are trying to uninstall is not installed. Debug logs generated using: msiexec /i AvamarClient-windows-x86_64-<client-version>.msi /L*v logxxx.txt show entries similar to: VALIDATEUPGRADETABLE_ERROR Upgrade verification failed. Please try to run the installer again. MSI (s): Product: EMC Avamar for Windows -- Upgrade verification failed. Registry keys referencing older Avamar components may remain, even if: /avs folder still exists under C:\Program Files (x86)\avsAvamar icon appears in the status barBackup agent service is runningControl Panel shows no Avamar component installed

Cause

The issue occurs because remnants of a previous Avamar client or plug-in remain in the Windows registry after an incomplete uninstall.These remnants trigger the Previous Version Validation check during installation, causing the upgrade to fail.Root cause is typically environmental, such as: Corrupted Windows OS componentsMissing Microsoft updates This is not an Avamar product defect but an OS-level issue that interferes with uninstall operations.

Resolution

Permanent Solution Work with your System Administrator or Microsoft Support to resolve OS-level issues.Investigate registry inconsistencies or missing system updates.Fixing the root cause prevents recurrence.If Microsoft Support requires collaboration with Dell, create a Service Request for the Avamar Support team. Reference this KB in the request and clearly state what assistance is needed from Avamar Support. Microsoft Recommended Fix (OS Repair) In a past scenario, Microsoft Support identified missing PowerShell module folders under: C:\Windows\System32\WindowsPowerShell\v1.0\Modules Normally, this path should contain many subfolders, but only a few were present. To repair OS inconsistencies, run System File Checker (SFC): sfc /scannow Run this command in an elevated Windows Command Prompt.Description: /scannow scans all protected OS files and repairs them as necessary.After completion, the missing modules should be restored, and the Avamar client upgrade should succeed. Workarounds Disable Version Verification Install the client using the SKIPUPGRADEVERIFICATION flag: msiexec /i AvamarClient-windows-x86_64-<client-version>.msi /L*v logxxx.txt SKIPUPGRADEVERIFICATION="TRUE" This bypasses version checks and completes installation.Note: This does not resolve the underlying OS issue. Rollback and Reinstall Reinstall the previous client and plug-in, then uninstall cleanly before upgrading.Example steps: Uninstall Exchange plug-in and File System client (if present).Reinstall old client and plug-in using msiexec with logging enabled.Uninstall old components using msiexec with logging enabled.Remove or rename the /avs directory manually.Reboot the system.Install the new client and plug-in using msiexec with logging enabled. If Issue Persists Open a Service Request with Dell Support and provide the installation logs for further assistance.

Support Cases