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Unable to download/install ANY/ALL add-ons?

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"The add-on could not be downloaded because of a connection failure." error message shows up every time i try to download ANY add-on, not just 3rd party ones. I tried downloading imacros and adblock plus among a couple others but it keeps telling me it can't because of my connection, even though i can load any page on the internet and play online games just fine, and on Chrome and Edge browsers too,

Another annoying note is when I tried downloading older versions to see if that's the problem I keep getting these Secure Connection Failed messages along with a line of

An error occurred during a connection to addons.cdn.mozilla.net. The server uses key pinning (HPKP) but no trusted certificate chain could be constructed that matches the pinset. Key pinning violations cannot be overridden. Error code: MOZILLA_PKIX_ERROR_KEY_PINNING_FAILURE The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. Please contact the website owners to inform them of this problem.

"The add-on could not be downloaded because of a connection failure." error message shows up every time i try to download ANY add-on, not just 3rd party ones. I tried downloading imacros and adblock plus among a couple others but it keeps telling me it can't because of my connection, even though i can load any page on the internet and play online games just fine, and on Chrome and Edge browsers too, Another annoying note is when I tried downloading older versions to see if that's the problem I keep getting these Secure Connection Failed messages along with a line of An error occurred during a connection to addons.cdn.mozilla.net. The server uses key pinning (HPKP) but no trusted certificate chain could be constructed that matches the pinset. Key pinning violations cannot be overridden. Error code: MOZILLA_PKIX_ERROR_KEY_PINNING_FAILURE The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. Please contact the website owners to inform them of this problem.

Chosen solution

First thing to note: all of the discussion about ConnectSafe and DNS settings is completely outside of Firefox config.

ConnectSafe from Norton is just a DNS service that’s supposed to block malicious web sites. A couple other levels will also block based on content (i.e. parental control). As far as I know, the only way to use it is to set your DNS settings to use their servers (instead of your ISP). This can be done at the router level (to affect all devices connected to the router), or on an individual computer. See their site here: https://dns.norton.com

Note that some routers can intercept DNS lookups, and then perform the lookup itself, based on its own settings. Essentially an override. Consequently, you’re probably best off by starting with router settings instead of adjusting OS settings.

Check your current DNS settings. If a ConnectSafe ip address is specified (see their FAQ for the list servers), change it to something else (e.g. Google’s DNS is 8.8.8.8; alternatively change it to your ISP DNS..you’ll have to contact them).

Last I checked, ConnectSafe was listing a TTL of 10 minutes (600 seconds) for addons.cdn.mozilla.net, so you may have to wait over 10 minutes for the change to take effect. You may need to restart the router (to ensure its DNS cache is cleared).

For more additional instructions on updating DNS settings, try any of these: - your ISP support - Google - ConnectSafe FAQ

Finally, I see that Norton Web Safe has once again marked addons.cdn.mozilla.net as unsafe. https://safeweb.norton.com/report/show?url=addons.cdn.mozilla.net

It’s like Norton is trying to break Firefox.

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All Replies (5)

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Could you look at this recent post about one reason for the "connection failure" error being Norton ConnectSafe DNS: https://support.mozilla.org/questions/1183370#answer-1054133

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Thank you!! I see, I do get that warning message. I don't know much about these things so I just wasn't sure what was going on. How would I adjust DNS settings to not use Norton ConnectSafe..? I've been going crazy the past few days trying to get add-ons installed haha, reinstalled Firefox at least 2-3 times already

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Hi Feralviper, I don't use Norton myself so it's difficult to make specific suggestions. Let me mention your thread over there and see if the Norton user can help you.

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Chosen Solution

First thing to note: all of the discussion about ConnectSafe and DNS settings is completely outside of Firefox config.

ConnectSafe from Norton is just a DNS service that’s supposed to block malicious web sites. A couple other levels will also block based on content (i.e. parental control). As far as I know, the only way to use it is to set your DNS settings to use their servers (instead of your ISP). This can be done at the router level (to affect all devices connected to the router), or on an individual computer. See their site here: https://dns.norton.com

Note that some routers can intercept DNS lookups, and then perform the lookup itself, based on its own settings. Essentially an override. Consequently, you’re probably best off by starting with router settings instead of adjusting OS settings.

Check your current DNS settings. If a ConnectSafe ip address is specified (see their FAQ for the list servers), change it to something else (e.g. Google’s DNS is 8.8.8.8; alternatively change it to your ISP DNS..you’ll have to contact them).

Last I checked, ConnectSafe was listing a TTL of 10 minutes (600 seconds) for addons.cdn.mozilla.net, so you may have to wait over 10 minutes for the change to take effect. You may need to restart the router (to ensure its DNS cache is cleared).

For more additional instructions on updating DNS settings, try any of these: - your ISP support - Google - ConnectSafe FAQ

Finally, I see that Norton Web Safe has once again marked addons.cdn.mozilla.net as unsafe. https://safeweb.norton.com/report/show?url=addons.cdn.mozilla.net

It’s like Norton is trying to break Firefox.

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oilblue99 said

Finally, I see that Norton Web Safe has once again marked addons.cdn.mozilla.net as unsafe. https://safeweb.norton.com/report/show?url=addons.cdn.mozilla.net It’s like Norton is trying to break Firefox.

The problematic version 2.0.0 of the "Open With Adobe PDF Reader" extension identified on that report page has been removed from the Add-ons site, so hopefully Norton will clear the server again soon. They are providing a useful service identifying individual problem extensions, but blocking the entire domain is definitely overkill.

Of course, Firefox's built-in download blocking (based on Google's Safe Browsing service) works the same way, but due to user pressure, Firefox also has an override button for cases where the user still wants the download. It's difficult to picture how that could be done in this case because the request occurs in the background.