Texture2D.Compress() method compress texture correclty, but writes errors in console:
d3d: failed to create 2D texture id=1289 w=1 h=1 mips=1 d3dfmt=894720068 [invalid call]
RGBA(1.000, 0.000, 0.000, 1.000)
UnityEngine.Debug:Internal_Log(Int32, String, Object)
UnityEngine.Debug:Log(Object)
Script:Start() (at Assets\Script.cs:16)

(Filename: Assets/Script.cs Line: 16)

failed to create 2D texture

(Filename: C:/BuildAgent/work/1562415f59e0ded/Runtime/GfxDevice/d3d/TexturesD3D9.cpp Line: 244)

!texture.texture

(Filename: C:/BuildAgent/work/1562415f59e0ded/Runtime/GfxDevice/d3d/TexturesD3D9.cpp Line: 591)