Today’s Question: What type of problems will I run into if I uninstall and then re-install Lightroom Classic? I will back up my catalog prior to the uninstall step.
Tim’s Quick Answer: If you choose the “Keep” option for preferences during the uninstall step, you won’t lose anything with this process. In particular, uninstalling and reinstalling Lightroom Classic won’t have any impact on your catalogs or photos.
More Detail: When you uninstall Lightroom Classic using the Creative Cloud application (which is the recommended approach) you’ll be asked if you want to keep or remove the preferences for Lightroom Classic. As long as you choose the “Keep” option you won’t cause any issues with Lightroom Classic.
If you’re having issues where you suspect that preferences files are corrupted, which is the reason you want to uninstall and reinstall, you can choose the “Remove” option instead of “Keep”. That means you’ll lose the settings for Preferences and Catalog Settings, causing those to revert to the default settings when you reinstall Lightroom Classic.
While losing your settings for Preferences and Catalog Settings can be a bit of an inconvenience, that just means you need to go through those two dialogs and update the settings based on your own preferences.
But again, this process won’t affect your catalog files or your photo storage, so the only potential issue would be having Preferences and Catalog Settings revert to their default settings.

