What does it say? Screenshot of the error?

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and
• Remove Cookies

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Cookies; Delete cookies to remove the information websites have stored on your computer {web link}

• Cache; How to clear the Firefox cache {web link}

If there is still a problem, Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Did this help?

While you are in safe mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

Such a message can be generated by a filter protecting the server against misuse.

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox from this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data from that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

The message I get is still: Forbidden

You don't have permission to access / on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

Please provide a public link (no password) that we can check out. No Personal Information Please !

This can happen if the website is down for maintenance or otherwise not available.

Note that other browser may show a cached page, so you can try a reload and bypass the cache on the other browsers.