After ugrading to 4.26 I had this error too for a texture. This likely resulted in an earlier not fully performed file move operation, leaving behind a corrupted texture at the original location.
To fix this, browse to the folder with the texture and check file size, if wrong file size, replace with original. Also check file references. IF no texture is visible from the engine browser, close the engine and open the file location in explorer, then delete the file. If references were in place, create anew texture with the same name at the location.