Exasperating!! just got an error message saying "Your ebay purchase was declined because you used a virtual card number you created for ebay... Use a virtual card number created for ebay to retry this purchase." ABSURD!!! it fails more often than it works, I give up. I'm taking it off my extensions.

No longer working after update. It always tells me to sign on by browser. However the pop up opens then shrinks and disappears each time.

As many other users mentioned, this stopped working the last time Capital One put out a new version about a month ago.
For me, when I click on the Eno logo and "Checking Session" appears, if I need to sign in a new window pops up for the login but then immediately shrinks and closes with out giving me the opportunity to put in my credentials. I was able to make it work again for 2 uses by uninstalling and reinstalling the add-on. Also, the work arounds others mention, go sign into C.Ones website, then open a new tab (or three) on the same retailer allow me to struggle through.
Honestly, I may drop Capital One if this isn't fixed, there are competitors with apps that work.

PLEASE MAKE IT WORK WITH FIREFOX!

THE WORK AROUND WORKED FOR ME - As with other reviews here, the ENO add on quit working easily - when I went to add a new virtual card, I had to sign into Capital One and then all it did was take me to the page that showed all my virtual cards BUT THEN I followed the advice of another review and logged into Capital One first, went to a website I wanted a virtual card for and ENO popped up automatically and created the new card. I gave three stars bc having to login to Cap One first shouldn't be a requirement but I LOVE the virtual card.

Plug in started blocking all content on multiple pages, some merchants some non-merchants (blank pages load with plugin enabled, content loads when it's disabled). Also doesn't remember login details.

Was on phone with C1 tech support. After explaining the issue multiple times, the call randomly went dead (no audio), before they understood the problem.

The app used to work fine. However, as of 10/25/21 it just pops open a window showing my existing virtual cards but doesn't allow me to create a new one.

Great when it works but way too often it tells you to sign in and doesn't recognize when you do. SUPER-frustrating.

virtual card will not add new maechants

Used to work, now broken as other reviewers have noted.

Doesn't work consistently but works great when it does work.

I have had the same problem so well described by other reviewers for about a month. It used to be a great add-on! "This addon has effectively been nothing more than a way to log in to the Virtual Cards page of the Capital One site for MANY versions now. It does not create new Virtual Cards and does not allow you to lock or unlock existing Virtual Cards. This is all but useless for anything other than getting you to the Capital One page that allows you to see your existing Virtual Cards. This addon has been the one and only way to create new Virtual Cards since their inception (you can't do that on the website), but now even this addon doesn't do that." When Eno stopped working a year or so ago, Capital One blamed Mozilla and I am sure Mozilla blamed Capital One. I wish they could work together to fix the current issue.
I tried the solution mentioned by Crix, but it didn't work. Not sure what adblock is or how to disable it.

when it works it works, but then it just breaks for no reason and you can utilize it. They just need to have this functionality on their own website or app, because this is annoying

After reading the most recent reviews, I almost didn't install the extension. However, I figured, if I install it and it doesn't work, I'll just remove it. But, if I give it a try and it does work, I've gained a tool that will fit my needs.

I'm happy to say that I installed the extension and it does in fact work. I'm running Firefox 93.0 (64 bit) on a desktop computer that's only a year old with Windows 10 Home for an OS. I downloaded Eno ver. 3.6.1

I will admit, I can see why some may have had difficulties in using the extension. It seems to have an issue with signing in to a Capital One account directly from the Eno extension. However, here's what I found to work for me. I log in to my Capital One account first through the Capital One home page (as I would if I was going to check account transactions for example.) Once I'm signed in, I then click on the Eno extension icon in the upper right hand corner of the Firefox browser. Eno will usually recognize my account at that point. From there, I go to the merchant of choice, navigate to where I would enter my credit card info, click on the Eno icon if it's not already open, then click "Use". Eno guides me through creating a new virtual number like it's supposed to. No issues.

If my Captial One account times out on it's own, Eno is also logged out of my account. This is by design and keeps my account secure. However, attempting to log back in to Eno can be finicky. Here's 2 work-arounds that consistently work for me. Right-click on the Eno icon and select "Manage Extension." Disable Eno by clicking on the little toggle switch. Then re-enable. If that doesn't work, disable Eno again and close the browser. Now re-open browser. Log in to your Capital One account next before enabling Eno. After you're logged in, enable Eno from the Add-ons Manager in Firefox (if the Add-ons Manager tab is not already open, click on the "More" button which is 3 horizontal lines in the upper right corner, then click on "Add-ons and themes").

To reiterate, I have found these 3 basic procedures to be very helpful:
1. Sign in to your Capital One account first before attempting to use Eno.
2. Know how to disable and re-enable Eno. Use as needed.
3. Close browser and then re-start browser as needed.

I also noted that some reviewers expressed difficulty with the Eno extension slowing down internet browsing. I have not experienced that yet. However, disabling the extension can be done easily when it's not needed to speed things up if necessary.

I feel that this extension is worthwhile to try downloading and using. The extension is pretty intuitive. The settings are simple and clear. The extension will walk you through the process of creating a virtual card number in just a couple steps. Eno even automatically adds the card number in the appropriate field on some sites. If it doesn't add it automatically, just left-click the copy icon next to the virtual number and then right-click in the card number field on the merchant site and click "paste."

Another nice feature is that when you create a virtual card number, you can set a time limit on how long that number will be active.

I'm quite happy I took the leap and gave it a try. I don't always like to try new things as there's a learning curve and I often don't feel I have the time. However, dealing with a fraudulent charge on a credit card also takes time (this happened to me recently.) Since the virtual card feature has the potential to protect my main account and physical card number, the little bit of time it takes to use Eno is worth the time it saves in the long run.