MultiMC

You should ALWAYS make backups before updating.

As with any other piece of software, updates may go wrong for many reasons, including but not limited to: the launcher, the hardware, your custom configuration, the mods you added... and, rarely, FO as well.

If you had installed FO on MultiMC with automatic updates, and you're not updating to a newer version of Minecraft, you just need to open the existing versions.

If you get a popup saying This modpack uses new versions of the following..., click on the Update button.

If you had installed FO on MultiMC without automatic updates, or if you're updating to a new version of Minecraft:

1. Follow the FO installation instructions for MultiMC again. This will create a new instance

2. In MultiMC, click on the previous version

3. Click on Minecraft Folder

4. Click on the new version as well

5. Click on Minecraft Folder

6. Copy the following files from the folder you opened in step 3 to the folder you opened in step 5:

   • saves: Your local worlds

   • resourcepacks: Your resource packs, if any. If you're asked to replace files, do not!

   • shaders: Your shaders, if any

   • screenshots: Your screenshots, if any

   • server.dat: Your multiplayer servers, if any

   • options.txt: Your custom options and keybinds, if any. If you want the recommended FO settings, do not copy it

7. Once you've moved them, launch Fabulously Optimized. Minecraft should open up

8. If you can see the newly installed version in the bottom-right corner, you can delete the previous version from step 2