Materials issue

I opened an old project I worked on months ago and the Materials are not loading, they are just the same default pattern. The Material files are there with their nodes connected but they aren’t loading. This happened all of the sudden, I didn’t change anything and I’m using the same version of the engine. I tried on Windows and Mac (The original OS used) and still the same.

I opened a random material and noticed that it has some errors there, but the others are apparently ok.

Please, any way of solving this?

Im no expert in these matters but with all the updates that are released some times errors occur after these updates. Sorry if you have tried already but have you tried to re-import the texture files for the materials in question? a screen shot of the actual material nodes may also be a bit more helpful even if just one.