Texture Errors

Rimsort and Rimpy are great mod managers for their own reasons but one of the more neat things they can do is optimize your textures, though in this more recent version of Rimworld (1.6) it will break certain mods textures. This is because rimworld now natively supports .DDS image file format.

There are some mods you can and some mods that you cannot optimize.
From my issues some of these mods are:

RPG Style Inventory Revamped
No ZZZ
No Healing Emotes
Vanilla Textures Expanded
Gerrymon's Upscaled Vanilla Textures
Warehouse Storage
Xercanine's Small Table
[CAT] Show Hair With Hats or Hide All Hats
Simple Blinking Animation
Anthrosonae Simple Blinking
Deep and Deeper
Camera+ o7 Brrainz
All/Most Dark Ages Mods
All/Most Hair mods
All/Most Vanilla Races Expanded Mods
Quarry Including any Retextures

Any mods that change textures of other mods are included in this list as well.
And if there is any other mods that cause these errors please write them down in the comments so I can write them here for others.

Most people when answering the question to, "Why are my textures giving errors." give the answer to use the neat mod Image Opt.

This mod is practically the same as Rimpy or Rimsort's Texture Optimization but it is used within Rimworld itself though in my time using it it doesn't help and rather gives you a even more worrying ? texture. This alternative error texture is sort of the same thing as the X texture error but I've seen being caused by Image Opt, if you specifically know why this is please tell me.

For now I would not use Image Opt and instead use Rimpy or Rimsort if you need to optimize textures.

Errors are caused by textures being changed by Mods or Applications,
specifically Image Opt, Rimsort and Rimpy.
Also you can find which mods are giving errors by looking in debug logs and finding the mods ID