@SirBoston, try verifying the integrity of the game cache.

I have tried verifying the game cache, I've uninstalled all anti virus programs, redownloaded, deleted all system files and redownloaded, restarted computer...

Hello SirBoston,
you're missing the core .NET Framework library which is required to run Arma 3 Launcher. Please try to re-install the latest .NET Framework to fix the issue: http://go.microsoft.com/fwlink/?LinkId=780601

I've tried that before and it always says that I have it already installed on this computer (version 4.6.2 or later). Should I just try to uninstall it?

You can try to uninstall it and install it again (I'd suggest to restart the computer in between) or try to use this tool Microsoft .NET Framework Repair Tool: https://www.microsoft.com/en-us/download/details.aspx?id=30135

Uninstalling and installing it again has not worked. The file doesn't even appear in the Microsoft Control Panel - Uninstall Programs. I've also tried repairing it which doesn't work.

That means that your Windows version has this .NET Framework already implemented as part of the system. So you have to run the check on the system itself:

1. Find Command Prompt in start menu and start it as administrator (right click on it, select Run as Administrator);
2. Enter the following command to initiate system check: sfc /scannow and press ENTER.
3. Enter the following command: Dism /Online /Cleanup-Image /RestoreHealth and press ENTER.

https://answers.microsoft.com/en-us/windows/wiki/windows_10-update/system-file-check-sfc-scan-and-repair-system-files/bc609315-da1f-4775-812c-695b60477a93

I have run the commands several times as suggested by the link you sent me and then restarted my computer. It seemed to work, saying that it found and repaired systems and such. I then tried running Arma 3 and it didn't work. I then tried re-downloading Microsoft .NET Framework and using the repair tool, but to no effect.

Hello? It's still not working and I've tried it again and again.

Hello SirBoston,
I'm sorry for the delay, I didn't forgot about you, but rather run out of options that can be easily done.

Could you please check that you have this file present on your PC? "C:\Windows\Microsoft.NET\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll" And if so please upload it to VirusTotal.com and post the link to result here, I'd like to check if the file is correct.

Okay here is the link: https://www.virustotal.com/en/file/d07b38d66c73ecda293c93643795a1f5d8b93d1e8685b243955cb0c31acddfb1/analysis/

Hello,
according to the report its an entirely different file "System.Management.Automation.dll", not "System.dll".
Are you sure that you've send a report for the correct file?

Browsing through the files, my files are different from "System" and on. I have "System.Management.Automation". If that's the correct file, then I have the "v4.0_3.0.0.031bf3856ad364e35" file, then all I have in that file is an application extension called: "System.Management.Automation.dll". C:\Windows\Microsoft.NET\assembly\GAC_MSIL\System.Management.Automation\v4.0_3.0.0.031bf3856ad364e35
Maybe my version is different, as I have "v4.0_3.0.0.0...", and my system needs update?
Here's the "System.Management.Automation" file if you need it:

Also, I just attempted to run my Arma 3 in compatibility mode and an error came up. Here are the details:
Package ID: PCWDiagnostic
Path: C:\WINDOWS\Diagnostics\Index\PCWDiagnostic.xml
Error Code: 0x80070002
Source: Engine
User: DESKTOP-FB87KV4
Context: Restricted

In the correct installation of .NET Framework, there have to be a System.DLL on the exact path I've posted before. Otherwise the game launcher (and many other applications build on .NET Framework 4) can't work.

I've uploaded the file from my PC (http://arma.jiripolasek.com/files/NETFramework4-System.zip), so you can unpack it to C:\Windows\Microsoft.NET\assembly\GAC_MSIL - the whole path should then be C:\Windows\Microsoft.NET\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll.

Edit: the original file should be also here: "C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.dll". If the file is there, you should take it from there first.

But I found it really strange that both .NET Framework Repair Tool and the system checks would be missing this.

In T122375#1556435, @SirBoston wrote:

Error Code: 0x80070002

It seems the System.dll won't be the only thing missing from your PC. According to the error code, Program Compatibility Wizard Troubleshooter (PCWDiagnostic) can't run because it can't find some file.

Again, this is very strange as such a file would be definitely part of Windows installation and should be repaired by the SFC / DISM tools.

I have replaced the files correctly and have failed to run Arma III, also tried deleting the other system file, and then failed to run it again.

And I do have "C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.dll"
Should I delete it?

In T122375#1556907, @SirBoston wrote:

And I do have "C:\Windows\Microsoft.NET\Framework\v4.0.30319\System.dll"
Should I delete it?

No, keep the file where it is.

In T122375#1556848, @SirBoston wrote:

I have replaced the files correctly and have failed to run Arma III, also tried deleting the other system file, and then failed to run it again.

Arma3Launcher_Exception_20170101T234513.txt3 KBDownload

Is there anything else that I can do to fix it?

According to the log, it's the same kind of error, this time for a different file. I've done some tests and it seems that Microsoft doesn't have any consumer tool to fix your issue. Normally this error is fixed simply by running the installer again, but as you can't run it, there's no easy way to fix it.

Should I attempt to contact Microsoft for any solutions?

Please?

I believe that the problem has to be between the launcher and the game, as third-party launchers have failed to work as well with the same problems. I'm able to start up the game by going through the file and directly starting the game up, but I need mods to play with friends. I can't figure out a way to use mods without a launcher and would like to get some more help. I hope that this helps to solve the issue. Thanks.

Hello SirBoston,
I'm afraid that you issue is not related to the game, nor anywhere between Launcher (or the other launcher) and the game.

We've already established that your .NET Framework 4 installation is corrupted, so you can't run any application that is based on .NET Framework 4. And as it happens, the most game launchers also uses the .NET Framework 4 (A3Launcher, WS Launcher, Survival Launcher,...).

I've been discussing this from engineer at Microsoft and from theirs point of view the only correct solution is to restore the operating system from backup or to restore it to default.

The only other solution we've came up with, is re-register the libraries using Windows dev tools:

1. You would have to download Windows 10 SDK from https://developer.microsoft.com/en-us/windows/downloads/windows-10-sdk and install .NET Framework Tools.
2. Run Visual Studio Command Prompt program in your start menu as administrator.
3. Run a following batch file in that command prompt: http://arma.jiripolasek.com/files/reinstall-netfx4-assemblies.zip

Note: there's no guarantee this will work, use it at your own risk, these tools are originally meant for developers

I've tried running the developer installation wizard thing, and it won't work. It opens up for a flash and then it crashes with no error message. The batch file works, though. I've been working with a friend, and we found a way to open the game from the folder file without steam and the launcher, which works, but it lacks the updated mods that I want to play the game. I'm still looking to repair my Microsoft Framework, etc., because other games like Terraria, don't work as well due to somewhat similar issues.

I have tried inserting the batch file into the command prompt, but I'm not sure if I'm doing it right.

*I've had a friend teach me about batch files, I'm good on that, but I still can't download the developer tool.