Update to Exchange Server 2019 CU15 fails with error 1612

Question

I have tried to update to CU15 but it fails when it starts to install Language files language 'am'. From what i read i have to use Volume Licensed version of the CU15 that i dont have. I don't have access to VL and i dont know how was it installed in the first place. Can someone help me with this?

[07/06/2025 19:04:21.0526] [1] Beginning processing install-LanguageFiles

[07/06/2025 19:04:21.0543] [1] Uninstalling the old client language pack for language 'am'.

[07/06/2025 19:04:21.0705] [1] ProductCode is 'dedffb64-42ec-4e26-005e-430e86df378c'.

[07/06/2025 19:04:21.0764] [1] Active Directory session settings for 'Uninstall-MsiPackage' are: View Entire Forest: 'True', Configuration Domain Controller: '', Preferred Global Catalog: '', Preferred Domain Controllers: '{ }'

[07/06/2025 19:04:21.0764] [1] User specified parameters: -LogFile:'C:\ExchangeSetupLogs\Uninstall.am.Client.20250706-210421.msilog' -ProductCode:'dedffb64-42ec-4e26-005e-430e86df378c'

[07/06/2025 19:04:21.0765] [1] Beginning processing Uninstall-MsiPackage

[07/06/2025 19:04:21.0777] [1] Removing MSI package with code 'dedffb64-42ec-4e26-005e-430e86df378c'.

[07/06/2025 19:04:58.0100] [1] [ERROR] Couldn't remove product with code dedffb64-42ec-4e26-005e-430e86df378c. The installation source for this product is not available. Verify that the source exists and that you can access it. Error code is 1612.

[07/06/2025 19:04:58.0100] [1] [ERROR] The installation source for this product is not available. Verify that the source exists and that you can access it

[07/06/2025 19:04:58.0102] [1] [ERROR] Couldn't remove product with code dedffb64-42ec-4e26-005e-430e86df378c. The installation source for this product is not available. Verify that the source exists and that you can access it. Error code is 1612.

[07/06/2025 19:04:58.0102] [1] [ERROR] The installation source for this product is not available. Verify that the source exists and that you can access it

[07/06/2025 19:04:58.0109] [1] Ending processing Uninstall-MsiPackage

[07/06/2025 19:04:58.0113] [1] [ERROR] Couldn't remove product with code dedffb64-42ec-4e26-005e-430e86df378c. The installation source for this product is not available. Verify that the source exists and that you can access it. Error code is 1612. It was running the command 'Uninstall-MsiPackage -LogFile 'C:\ExchangeSetupLogs\Uninstall.am.Client.20250706-210421.msilog' -ProductCode 'dedffb64-42ec-4e26-005e-430e86df378c''.

[07/06/2025 19:04:58.0113] [1] [ERROR] Couldn't remove product with code dedffb64-42ec-4e26-005e-430e86df378c. The installation source for this product is not available. Verify that the source exists and that you can access it. Error code is 1612.

[07/06/2025 19:04:58.0113] [1] [ERROR] The installation source for this product is not available. Verify that the source exists and that you can access it

[07/06/2025 19:04:58.0130] [1] Ending processing install-LanguageFiles

Answer 1

Hi @Aleksandar Maksimovski 
Thanks for reaching out to the Microsoft Q&A forum and sharing the details of your issue. 
Based on your description, it seems you're encountering a failure during the installation of Exchange Server 2019 CU15, specifically related to the language files for language 'am'. 
As a forum moderator with limited access to dedicated testing environments, I may not be able to provide a precise solution tailored to every unique scenario. That said, your input is incredibly valuable in helping us narrow down the issue and offer more targeted support. 

To assist you better, could you please share the exact command you're using to initiate the update, or any other relevant setup details? Having a clearer picture of your update process will help us refine our research and provide more accurate guidance. 

In the meantime, please ensure that your Exchange setup is pointing to the correct Exchange Server 2019 ISO file. This is a common source of issues during cumulative update installations.  For step-by-step instructions on updating to the latest CU, please refer to the official Microsoft documentation: Upgrade Exchange to the latest Cumulative Update | Microsoft Learn 

Additionally, here’s a related case that might offer some insights. While it may not exactly match your situation, it could still highlight useful points worth reviewing: Exchange 2013 cannot upgrade from CU9 to CU23 without the CU9 install media - Microsoft Q&A 

If I’ve misunderstood any part of your issue, or if you have any updates to share, please don’t hesitate to reply. Your feedback is crucial in helping us find the best solution for you. 

Thank you for your understanding and patience as we work through this together!   

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