Hi, one of your add-ons (extensions) is interfering with the website. Enable them one by one until you find the culprit. You may need to restart Firefox after enabling some extensions.

It's not unusual for things like that to happen. You may be able to leave feedback for the add-on's developer on the add-ons page. Failing that, since it isn't a Firefox issue, there is nothing else you can do.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you!

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block (wanted) content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows the shield icon at the left end of the location/address bar in case content is blocked by Tracking Protection.

• click the shield icon for more detail and possibly disable the protection
• You can check the Web Console by Tracking Protection
• "3-bar" menu button or Tools -> Web Developer
• https://support.mozilla.org/en-US/kb/tracking-protection-firefox

Thank you both.

I went through each add-on one at a time and it seems that the DuckDuckGo Privacy Essentials are the culprit.

I do run ad blocker, but I always disable on a particular site if I'm having a problem. On the computer that had ad blocker running, I disabled that and it works.

I am not able to access the third computer until tomorrow and I can test there as well.

I also had to shut off private browsing on one of them.

Could you comment on why this is true of this site but not others?

Also, why would it allow to add to cart from category page and not the product page? What would be the difference between the two?

I can make changes to this site so that information would be helpful.

@ssrw, if you want other to test what your asking a link would help others figure out what your saying otherwise this is just tossing around words and no one can see what is happening. As as mentioned in the solved reply addons issue are not a FF Browser issue.

The situation is not consistent on all computers. I've tested on other computers and works just fine in private mode.

In Private Browsing mode Tracking Protection is active by default, although you can enable TP in regular mode as well. You will see a the shield icon at the at the left end of the location bar in case content is blocked.

I think that DuckDuckGo Privacy Essentials uses a blocklist similar to Tracking Protection, only you won't see the shield, but possibly see badges attached the DPE toolbar icon.

ssrw said

I also had to shut off private browsing on one of them.

Unless someone jumps in here and says otherwise, I do not use the Private Browser with shopping sites. I've shopped using the regular browser for decades this way, in IE and now FF. Too many problems when using the Private Browser.

Any Security and Tracking Extension can mess-up some site navigation. I also had my share of problems across some sites with DuckDuckGo. It messes up when a site uses a mix of HTTPS and HTTP. I'm thinking of deleting it.

Attached are my Security and Tracking Extensions.

~Pj

The thing that's really stumping me is that I've never had a problem on any site with this before. Just this one site.

What content blocking extensions do you have?

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

I have had trouble loading the checkout and review pages of shopping sites. Trouble occurs with regular FF, not private FF. Sure wish the security hints at the top told me why the page was not loading so I could make a more intelligent choice about what to do, rather than just opening up everything.

bscranton said

I have had trouble loading the checkout and review pages of shopping sites. Trouble occurs with regular FF, not private FF.

• Private Browsing can cause problems, even though it helps you in some cases, like you stated.

• However, it's best overall to use non-Private browsing and White-List all Shopping sites. Turn-OFF FF's Tracking Protection and use an Extension for Track-Blocking or White-List Shopping sites in the Tracking Protection drop-down at the left of the URL.

• Some Blockers are Blocking Google's URLs that have the words Tags, Analytics, and APIS (Fonts). Make sure to check if a Blocker is blocking one of these. A problematic Website may work if one or more of these are unblocked. (Based on my experience so far.)

~Pj