If you're using a cracked launcher or switched from a cracked launcher to the official launcher, it's due to corrupted assets.

If you're using MultiMC, it's due to missing assets. Try running a vanilla instance and copying the assets, or copy the assets from the normal launcher.

If you're on the normal launcher, use F3 + T or run a vanilla profile to load the assets. If it doesn't work, delete the assets folder and run vanilla again, then run Aristois after.