If you're unable to open a specific website using Firefox Nightly, you can try the following troubleshooting steps:

Clear browser cache: In Firefox Nightly, go to the menu (represented by three horizontal lines in the upper-right corner) and click on "Options." Then, select "Privacy & Security" from the sidebar. Under the "Cookies and Site Data" section, click on "Clear Data" and select "Cached Web Content." Finally, click "Clear" to clear the browser cache.

Disable browser extensions: Some browser extensions or add-ons can interfere with website functionality. Temporarily disable all extensions in Firefox Nightly by going to the menu, selecting "Add-ons," and then disabling each extension individually. After disabling the extensions, try accessing the website again.

Check firewall or antivirus settings: Your firewall or antivirus software might be blocking access to the specific website. Temporarily disable the firewall or antivirus software and try accessing the site. If you can access the site after disabling the firewall or antivirus, adjust the settings to allow access to that particular website.

Disable VPN or proxy: If you're using a VPN or proxy service, it might be causing connectivity issues with the website. Temporarily disable the VPN or proxy and try accessing the site again.

Try a different browser: Test if the website opens in a different browser, such as Google Chrome or Microsoft Edge. If it does, the issue may be specific to Firefox Nightly.

Update Firefox Nightly: Make sure you are using the latest version of Firefox Nightly. Go to the menu, select "Help," and then click on "About Nightly" to check for updates. If an update is available, install it and try accessing the website again.

Reset Firefox Nightly settings: If none of the above steps work, you can try resetting Firefox Nightly to its default settings. Open the Firefox Nightly menu, click on "Help," and select "Troubleshooting Information." In the Troubleshooting Information page, click on the "Refresh Nightly" button to reset Firefox Nightly.

Regards, Peter

Works for me in nightly.

You can remove all data stored in Firefox for 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 for this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data for that domain that you do not want to lose, 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, data for that website will be saved once again.

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

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works, you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile