Install any previous version of Lightroom Classic CC 7.x (from versions 7.0 through 7.5) using the Creative Cloud desktop app. See Install previous version of your Creative Cloud app.
Lightroom Classic CC 8.0 (October 2018 release) crashes during launch on Windows. This issue can occur when Lightroom Classic's language preference is set to Automatic (default) while your operating system's language is set to a language that is not supported by Lightroom Classic.
Lightroom Classic CC 8.0
To resolve this crash issue, use any one of the workarounds listed below on your Windows computer.
After installing the previous version, launch Lightroom Classic.
From the menu bar, choose Edit > Preferences.
In the Preferences dialog, go to the General tab. Set Language to English and click OK.
Quit Lightroom Classic.
Update Lightroom Classic to the latest version using the Creative Cloud desktop app. See Update Creative Cloud apps.
Launch the app after installing the latest version. The crash issue should now be resolved.
Before you begin, it is recommended that you back up the registry. See Microsoft's documentation: How to back up and restore the registry in Windows.
Open the Registry Editor.
Press Windows + R keys or choose Start > Run. In the Run dialog, type regedit.exe and click OK.
If you are prompted for an administrator password or for confirmation, type the password or provide confirmation. If you have restricted access to the Windows computer you're logged into, you may not be able to access the Windows registry. Ensure that you have administrative privileges on your computer.
In the Registry Editor window, navigate to the folder path below:
Do the following:
a. Right-click the Adobe folder in the left pane. From the pop-up menu, choose New > Key.
b. Right-click this new key in the left pane and choose Rename from the pop-up menu. Type the name as Lightroom and press Enter.
c. Ensure that the Lightroom folder is selected. In the right pane, right-click anywhere in the empty area and choose New > String Value.
d. Right-click this new value entry in the right pane and choose Rename from the pop-up menu. Type the name as language and press Enter.
Proceed to the next step.
Right-click the language entry in the right pane and choose Modify from the pop-up menu.
In the Edit String dialog, type en in the Value Data field and click OK.
Relaunch Lightroom Classic. The crash issue should now be resolved.