I've been getting an 500 error everytime I tried to access the site. I've tried the solution posted in here but the SecurityTokenServiceApplicationPool is running normally. I also checked the event viewer and this is the error. Is there any way to fix this? I've tried creating another Site Collection and Web Application but still have the same results. Thanks
EDIT: I've fixed the problem by restarting the SharePoint Web Services Site in IIS. Thank you.