Uninstalling Old Versions of .Net Framework

Posted by JAFIOR@reddit | sysadmin | View on Reddit | 12 comments

I have a Windows 2019 server. It's a pretty basic machine not used for much of anything except managing storage systems. For some reason, it has several old .Net Framework versions installed, which I need to remove to comply with security policy. None of these old versions show up under P&F in the control panel. I DL'd the dotnet-uninstaller tool, and it didn't show any on the old packages either. I tried just blowing away the system files (dangerous perhaps, but I have good backups on file, so I'm not worried about breaking it). The system files were owned by TrustedInstaller, and wouldn't allow me to remove some of them. I have enough privileges with my admin account that I was able to change owner on the system files, but I'm still receiving permission denied errors when I try and delete them. Lots of googling, lots of attempted tricks and tips, no success. Does anyone have any idea how I might be able to accomplish this? Thanks in advance!

12 Comments

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dahud@reddit

What are the full names of the .Net versions you need to uninstall?

techvet83@reddit

Yes, what are the versions being called? You can just upgrade them. 2.0 and 3.5 are still supported. For 4.x, just move to the latest 4.8 version.

Breez__@reddit

2.0 is not supported anymore (since 2011) and should be removed. 3.5 SP1 is supported until Jan 9, 2029.

SysAdminDennyBob@reddit

You cannot have multiple version of .NET Framework, the exception to that is the enablement of .NET 3.5 as a Feature. .NET Framework is the old-school .NET that is tied to the OS. Are you maybe seeing install of .NET CORE? which is completely and entirely different unrelated component and there can be dozens of those on a box. If it is .NET Core then ask the DEV team that runs their app on the server which ones you can remove first. [Uninstall Tool - .NET | Microsoft Learn](https://learn.microsoft.com/en-us/dotnet/core/additional-tools/uninstall-tool?tabs=windows)

JAFIOR@reddit (OP)

Possibly. I'm pretty green, so still learning. If my understanding is correct, beginning with .Net 3.5, MS incorporated it into the OS rather than classified it as a separate app. So if it's an older version installed on a supported OS, it's still supported. But, when I look in c:\windows\program files\Microsoft.Net, there are folders for versions 1.0, 2.0, 3.0, and 3.5 along with the current version 4.x, and in those system folder, there are mscorlib.dll files, which the security guidelines I'm trying to follow say is the big no-no. The uninstall tool did not work in this case. Tried that yesterday.

Dude, if you try and gut .NET Framework on that server by grinding through the registry and file permissions you are in for a very bad experience. You are going to burn that system to the ground. Go into Windows Features and uncheck .NET 2.0 and 3.5. Your app owner will probably be calling you later to complain. .NET Framework including the weird legacy 2.0 and 3.5 are supported and secured via the OS dependency. A LOT of applications depend on those. Just keep the monthly .NET OS patches going every month or so when they appear.

No one except me uses this server. I have good backups on file (full image backups run nightly). I'm willing to break this server beyond salvation for the sake of learning, and I can restore it from backup anytime on-demand.

k, just be aware that those .NET 2.0 and 3.5 installs are not ancient standalone duplicate components. Those are modern well used parts of the Operating System. Just install .NET Framework 4.8.1 on the server and you are good to go. Every month the 2.0 and 3.5 are being updated. If you really want to remove .NET 2.0 and 3.5 do that as a Windows Feature.

Noted, and I really do appreciate the insight. As I said, I'm pretty green. I literally wouldn't even be trying to do this, but we have an upcoming company-wide cybersecurity evaluation coming up in a few weeks, and I was told I have to do this.

If you run a Nessus or Rapid 7 scan on server that has those .NET 2.0 and 3.5 items you will get a Compliant scan. I get that those version numbers look small and old but there is a very complex history as to why those are still around. Just be assured that they are patched and maintained by MS. Just look at the title of the current Operating System .NET patch below 2024-01 Cumulative Update for .NET Framework **3.5**, 4.7.2 and 4.8 for Windows Server 2019 for x64 (KB5034273) See that 3.5 in there? You are good.

Stormblade73@reddit

This. .NET 4, .NET 3.5 and .NET 2.0 are all built into the OS. .NET 3.5 and .NET 2.0 can be turned off by going to Add/Remove Roles and Features, and removing the feature ".Net Framework 3.5 Features" If the .NET you are looking for is a version OTHER than those listed above, then you have a major issue, as older versions cannot be installed on Server 2019. And above all else, make sure none of your applications require the versions you will be disabling....

jmbpiano@reddit

>I was able to change owner on the system files >still receiving permission denied errors The only reason I know of for both of these things to be true is if the file you're trying to delete is currently in use by a process somewhere. Given the nature of what you're trying to delete, that seems extremely likely. If you're absolutely bound and determined to delete files that the system probably expects to be there, your best bet is probably the delete-on-reboot [registry method](https://superuser.com/questions/58479/is-there-a-registry-key-to-tell-windows-to-delete-a-file-at-next-startup). I wouldn't be surprised to see stability issues after, though.

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