KB: Fail to launch Altium with no error message

Solution Details

• Press and hold down the Ctrl key while launching Altium
• Right-click on Altium icon and select 'Run as administrator'
• Remove preferences through uninstaller
• Update your video board driver(s)
• Check to see (and remove/disable) if you have any unused 3rd party software that may interfere such as nVidia nView Desktop Manager, Discord, or some antiviru software blocking X2.exe/DXP.exe or scanning every file as it's accessed.
• Verify firewall is not blocking X2.exe accessing the internet
• Try to remove hardcopy printer drivers
• Repair missing or corrupted Windows system files with Windows System File Checker tool

Run as administrator:

Launch Altium Designer by right-clicking on its icon and choosing "Run as Administrator".  If that succeeds, your Window account needs access permission to the following regitry and paths:

Registry keys:
- HKEY_CURRENT_USER\Software\Altium
- HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Start Menu\Programs\Altium
- HKEY_USERS\S-1-5-21-149779583-799757147-1568867282-45119\Software\Altium (The ID here is only a example-ID. It should show you only that the right key is the one with the longer ID.)
- HKEY_LOCAL_MACHINE\SOFTWARE\Altium
- HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Altium
 
Paths:
- C:\Users\Public\Documents\Altium
- C:\Users\<WIN-LOGINNAME>\AppData\Local\Altium
- C:\Users\<WIN-LOGINNAME>\AppData\Roaming\Altium
- C:\ProgramData\Altium
- C:\Program Files\Altium This folder is the installation folder of the Altium Designers. If you have installed Altium Designer at another location you have to setup the rights there.)
(C:\Program Files (x86)/Altium (for 32-bit versions)

Remove preferences:

From Windows Start button, launch 'add or remove programs', locate the installation instance of Altium, click to uninstall, and in the unistaller wizard dialog choose the option 'Remove Preferences':
https://www.altium.com/documentation/altium-designer/system-installation-licensing-management-overview#!uninstalling:~:text=another%20installed%20version.-,Remove%20Preferences,-%E2%80%93%20removes%20just%20the
Please note, this process will leave your Altium software in a freshly installed state, so if you connect to a private license server, please record the server information elsewhere before initiating.

Update your video board driver(s):
It's always a good idea to have the latest video board driver from the board manufacture's web page (rather than using Windows update or from Device Manager.)  You can use the Windows control panel ► Device Manager ► Display adapters, to see what's installed, then go to the manufacturer's web page to download and install the latest driver.

Check and remove any 3rd party software affecting:
NVIDIA nView desktop manager or RTX Desktop Manager (formerly Quadro View) is known to cause some incompatibility in the past where Altium only launch intermittently. 

Since there is no impact on the NVIDIA driver, uninstalling or just disabling the utility software resolves this issue.  The Windows taskbar should have an entry for NVIDIA Settings - it will appear as an icon in the system tray (notification area), next to the clock. Right-click and select nView Desktop Manager » nView Properties. The nView Desktop Management dialog appears. Go to the Desktop Management tab and click the Disable button.  Once the nView Desktop Manager is disabled, the button will say Enable.  Some have found that Altium won't start if NVIDIA Control Panel is running.  Check the notification area (formerly known as the system tray) and exit if it's running.  You may find the NVIDIA desktop manager in the Desktop menu.  Right click on an open area on the desktop, then select "Nvidia RTX desktop manager", then disable.  You may also try updating the version from https://www.nvidia.com/en-us/design-visualization/software/quadro-view/release-highlights/ .

Discord app has also been reported to slow down or crash Altium Designer.
https://support.discord.com/hc/en-us/community/posts/360070019571-There-is-a-bug-when-you-use-Altium-Designer
Verify antivirus software running on the machine is not blocking the startup process. (X2.exe or DXP.exe) Or scanning every file as it's accessed.
If you are using a program called autorun to turn off extra startup services/programs, and have turned off any Office related services, including “ClickToRunSvc”. Altium will crash when it tries to open a dblib that is based on an Excel sheet.

Verify firewall is not blocking X2.exe:
Verify your firewall is not blocking X2.EXE access to the internet in Domain, Private, and Public networks.  The network being used has to have "Network Discovery" and "File and Printer Sharing" turned on

Remove hardcopy printer drivers:
Try deleting all hard copy printers and say yes to remove drivers if asked.  This has been known to cause Altium to crash when saving the project as well.

Use Windows System File Checker tool to repair files:

1. Click on the windows start button
2. Type in CMD then from the results right-click on Command Prompt and select “Run as Administrator”.  You may need to click on yes to allow the app to make changes.
3. Type in “sfc /scannow” without quotes.  This process will verify their Windows Installation and replace any corrupted or missing DLL along with any other Windows protected system files.
4. Reboot the PC.

You may have a better chance with the offline installer if the source of the problem is in some network traffic blockage.

There may be some variations of warnings and errors below where tracing back on the exact source of the problem may be difficult, such that a complete re-install is highly recommended.

"Could not start Vault Explorer...":

"Unable to create .Net object...":

There is another article detailing this particular error dialog: https://www.altium.com/documentation/knowledge-base/altium-designer/resolve-popup-error-dialog-of-could-not-decompress-the-image-and-runtime-error-216