Do you mean Firefox's internal tracking protection feature that is still in testing? I would try without that, and also see whether you can make an exception in Privacy Badger which has been noted to break a few sites.

These obviously are general suggestions:

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click/Ctrl+click a blank are of the page and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or globe icon in the address bar > More Information > "View Cookies"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page and logging into Twitter again. Does that help?

Thanks for the tip, jscher! I disabled tracking protection and Privacy Badger on Twitter. Sadly, the issue still occurs upon refresh, restart, or disabling Privacy Badger entirely. I also start in private browsing, meaning that I'm good on cache and most cookies with none from Twitter taking disk space.

I also played around with the referer header, which may be to blame.

Could you post the exact wording of the error message? (To facilitate searching to see whether someone has found a solution.)

Here's the message, "Your account may not be allowed to perform this action. Please refresh the page and try again."

Strange thing is that I can tweet and favorite on every other browser--in this case being Safari and Vivaldi--but not Firefox.

Did you undo your tinkering with the referer header?

There are a lot of search results for that message. Advice includes:

• "Every time I've seen this, it's because I've already ReTweeted that tweet, and I'd forgotten."
• "Just wait 2 hours or more, and then your account can be used again."
• "try signing out then signing back in and repeat the action."
• "There are too many follows from your account, you have a certain number of API calls per hour and if you exceed them you are blocked from making more actions, you are also limited to a certain number per day and if exceeded will block them."

Etc. etc. I don't really see anything there that would explain a browser-specific issue.

In an earlier support thread, a Firefox Refresh/Reset resolved it, but that's a bit drastic: Can't tweet using firefox.

Yes I did and I can tweet again! Thanks for helping out!

This specific issue with twitter and a handful website is caused by the absence of referral information on image request.

Users of Configuration Mania extension or other privacy enhancing extensions may have configured the setting to withhold referral information, which leads to certain websites (e.g. twitter) to malfunction.

A focused solution is opening about:config and searching for the string network.http.sendRefererHeader this shall be reset to default either by right-clicking -> reset or editing the value to 2