Hi ZM-3283,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
It seems like you've encountered a language-related issue during the in-place upgrade process. Despite changing the language setting on the VM to English and restarting it, the upgrade still fails to keep your files and folders due to the language mismatch. I can suggest you with the following steps:
First, ensure that your system language matches the language of the Windows Server 2019 installation you are trying to perform. If the system language is different, you can change it to match the installation language.
Check System Language
If your files, apps, and settings can’t be kept because of the different language, you can try this way.
Step 1: Open Command Prompt (CMD) as an administrator in Windows 11/10.
Step 2: Type DISM /online /get-intl and press Enter. You can find what your system language is. If it is not English, continue the operation below.
Step 3: Restart Windows and press Shift to enter Windows Recovery Environment.
Step 4: Go to Troubleshoot > Advanced options > Command Prompt.
Step 5: Type DISM /image:C: /set-uilang:en-US and press Enter. Your system language will be set to en-US and you can keep your files during the in-place upgrade.
Change System Locale in Control Panel
To fix the error “your files, apps and settings can’t be kept” caused by a language, you can also try this way.
Step 1: Go to Control Panel via the search box of Windows 10/11. List the items by Category.
Step 2: Click Clock, Language, and Region to continue.
Step 3: Click Region and go to Administrative.
Step 4: Click Change system locale and set the current system locale to English (United States).
Step 5: Save the change and restart your PC. Then, upgrade Windows again to see if the issue is solved.
Change Registry Settings: If your files, apps, and settings can’t be kept because of the unsupported directory or current version of Windows, you can try to change registry settings which I assume is not your case.
If you have any further queries, do let us know.
If the answer is helpful, please click "Accept Answer" and "Upvote it."