@riennnnnnn No, these errors shouldn't be related. But it's always possible the same underlying change caused both. Please make sure the custom content is in the folder Sims 4 is actually reading. Find the full file path in-game:
https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/
Then compare that to the file path for a cc item. You can right-click that file and select Properties > General, then look at the Location.
If the skins in fact in the correct folder, please remove them and download and install a fresh copy of one of them, then see whether it shows up in-game.