Scan stuck 99% and same 2 reading errors

The read errors are probably just because the memory_limit is set too low in the php.ini file on your server. Try asking your hosting provider to help you increase your memory_limit.

Getting stuck in the cache folder could be problematic but the solution is simple, delete the cached files. You should not waste your time and CPU scanning cache files. Those files should be cleared anyway, especially if you have had any kind of infection on your site that might have been preserved in your cache. In addition, it’s a good idea to completely disable all caching on your site while you are working on cleaning up an infection so that you can be cure that you have got it all clean and only start building and storing cache once you are sure that it will not be contaminated by any active threats.