How to stop redirect from http:// to https://

My library's OPAC (online public access catalog) website doesn't currently use HTTPS. Trying to view it with a secure connection 'crashes' it regardless of browser. However once I accidentally tried to visit the site via HTTPS and now it automatically tries to serve me the secure version no matter what I do.

I've had the same problem in Chrome for a while, and while I can use the solution presented in this similar question and it will fix it for a little while by my next session the HTTP to HTTPS redirect is back in chrome.

For that reason I've been using Firefox mostly until today when I accidentally pasted an HTTPS link to the website into Firefox now Firefox will only serve the HTTPS version as well.

Exit Firefox and edit the file

/Users/Chloe/AppData/Roaming/Mozilla/Firefox/Profiles/xxxxx.default-999999/SiteSecurityServiceState.txt

Delete the line with your domain in it. Then restart Firefox. That will stop the redirection. That file is like Chrome's chrome://net-internals/#hsts.

The xxx and 999 will be random letters and numbers. The path is for Windows. Use Menu > Help > Troubleshooting Information > Profile Folder to find where your profile is located. In Linux the file is

/home/<USER>/.mozilla/firefox/profile.default/SiteSecurityServiceState.txt