Firefox Community Forum

I'm reposting a question already opened here because a moderator suggested to do so. Actually I though I was posting to the international forum from the URL...

I was trying to access a local HTTPS website of an embedded device (a Siemens S7-1500 PLC) that is using a self-signed certificate, but was unable to go on (attached image #1, in Italian language) due to the the SEC_ERROR_REUSED_ISSUER_AND_SERIAL error. I've browsed a similar PLC webserver in the past, so the fact that the device exposes a similar certificate serial number is not so strange for me, considering also it's self-signed.

The problem is that I cannot follow the instructions of the Mozilla knowledgebase here because I'm not able to identify the correct certificate of the website!

In the attached image #2 you can see that the connection is detected as not encrypted, I suppose because only the form part of the HTML that is posting the data using HTTPS while the rest is using HTTP, but I'm not sure. If I click on the padlock icon (attached image #3) the info about the current certificate is not displayed.

Then I went into Tools > Options and searched for "certificates"; as you can see in the attached images #4 and #5, neither in the Servers tab nor in the Authorities tab I can find any item that is related to 192.168.10.2 (the webserver IP address) or Siemens (the embedded device manufacturer). But unfortunately the error persist! Initially there was a 192.168.10.2:443 line in the Servers tab and I removed it and restarted Firefox, but it didn't solve, so at the moment the situation is the one depicted by the attachments.

I had to use Microsoft Edge to access the website, but I would like to solve this issue and use Firefox instead. Is there anything else I can do to bypass the error? Why doesn't the error page provide a way to correctly identify the wrong certificate using its fingerprint and/or name? Or, maybe, is there a way to disable this check for local IP addresses or for items in a whitelist?

Thanks for your help.

Hi, I am experiencing an issue with accessing my Amazon orders and returns when using Mozilla Firefox. While I can navigate to Amazon.com without any problems, I am now prompted to sign in to my Amazon account whenever I attempt to view my orders or returns. This pop-up indicates that it is a Firefox security issue rather than a Windows problem. This situation has only started occurring recently, and I would appreciate any assistance in resolving this matter. My Firefox version is 150.03. Thank you for your help.

Hi all,

After the last update the former Mozilla Test Pilot "Snooze Tabs" isn't working for me any more, I tell a tab to snooze and it just stays where it is. https://addons.mozilla.org/en-GB/firefox/addon/snoozetabs/

I've tried running with addons disabled and then running with addons active again and the behaviour is the same. It's the same behaviour whether I run from the toolbar or the context menu.

I'm presuming this problem is related to Firefox update mechanics. Any suggestions for how to get this working again please?

Cheers :)

Hi folks, my primary password suddenly stopped working when trying to look at saved passwords today. I've changed it to a new one, needing to type in the old password to do so. That worked, which verifies I had the correct password to begin with.

I then updated the browser to the latest version. When I type in the new password on startup of Firefox it works fine to reopen all the old tabs.

However when I go to look at any of the saved website passwords, the problem reoccurs again. I type in the new password but the box shakes, refusing it.

How can it be that the primary password lets me in fine when starting up Firefox, yet I get the shaking login box when I try to look at any saved website passwords? Surely if the primary password works for one it should work for the other?

Thank you, Shane

Hello brothers and sisters, i am need help! I'm experiencing performance issues when surfing the 9GAG website. The amount of RAM consumed by this page is growing exponentially. It's gotten to the point where this tab can consume up to 5GB of memory, and that's not the limit. This issue hasn't happened before. I can't figure out what's causing it.

What I did to fix the problem: I reinstalled the browser. I reinstalled add-ons. I reset my old profile, saving only bookmarks and passwords. I reinstalled the operating system. None of this helped. However, my friends don't have this problem with this site. Please help.

Hi all,

I have another query ongoing which trying to fix seems to have caused this problem: https://support.mozilla.org/en-US/questions/1581166

I'm logged into Firefox account and have everything synced. I've logged multi-account containers (MAC) into my Firefox to try and sync accounts. However, the containers are not syncing AND I now cannot send tabs to or from this instance of Firefox.

This started either after I refreshed Firefox or after I reinstalled it, I'm not sure which. Before Refresh I definitely had full sync, and I believe containers were synced but I had not changed anything in MAC for a long time, many months maybe years.

To try and fix this, I logged out of my Firefox account for both MAC and the whole browser, then closed Firefox. I then restarted Firefox, logged into my Firefox account and tested that I could send and receive tabs - I could, so that worked. I then logged into my Firefox account with MAC and tried to send a tab, and I couldn't, and nor did the containers sync. So, it seems that the MAC addon breaks sync.

A workaround is just to not depend on containers sync, but I'd prefer to get this back.

Any suggestions on how to fix this, or is this a bug in Firefox or MAC?

Cheers :)

An error occurred during a connection to tpz.sashacare.com. SSL received a record that exceeded the maximum permissible length.

We had a power outage in our area. Afterwards when the power was back on I could no longer get CNBC.com to work properly. It kinda opens but nothing goes live nor do the videos play. If I switch to Chrome everything works, but I like Firefox! Lynn Nichols

I've done recent updates (May 2026) and after having 3 updates in recent months, I still have difficulties with my video programs (both Zoom and "One-click) slowing down during my work which is 100% virtual. How can I revert to an earlier version where this was resolved, please!!??

Firefox runs some sites slows on one of my Windows 10 computers.

I'm running Firefox on 4 Windows PCs and 3 of the 4 work just fine using the same synced profile.

Fidelity.com and Amazon.com are 2 of the sites that are very slow to load. They will eventually load, but clicking on any links causes another slow load.

The same web sites are fast when I use MS Edge.

Troubleshooting steps I've taken (none of which have worked):

• Refreshed Firefox
• Created a new profile
• Uninstalled Firefox leaving my old profile
• Completely uninstalled Firefox and deleted my profile

Any thoughts on troubleshooting steps to take?

This has happened randomly on several different computers, both windows and ubuntu linux. It just now happened on my Win 11 computer. Was viewing the CNN news site and FF suddenly closed, without a "FF crashed..." message.When I clicked the icon to reopen it, it came up with the home page group of tabs instead of reopening the windows and tabs that were opened when it crashed. Worse, none of the previous months of history shows up and recently closed tabs and windows are both greyed out.

Is there a way of recovering the history of what I was working on at the time of the crash and what the hell is causing this? I am close to dumping FF and going with something else as this is highly annoying.

help me restore my open windows. this has also happened a couple times before and its very frustrating when i have tabs open to read/refer to later or am in the process of reading and then i have to try and find them all again.

Randomly my firefix just get loggedout and when i immediately logged it in again using mozilla i cant see my bookmarks my other accounts my profiles and all my groups and other information it was like i had made a fresh account all my data is lost what to do ? PLZ help i really want my data back i have been trying to get my data. Working on it for last hour.