I get the same. It's because the webpage has a 'form' to collect data such as your username and password. Which it sends off to
http://www.greenbuildingforum.co.uk/newforum/post.php

That is a 'http' address not a 'https' secure address (which they should be these days), so the browser has started flagging that up as a security problem.

The best solution would be for someone to update all the links hidden in the workings of GBF, so they all go to https not http.

As the customer support muppets regularly say: "Can you try a different browser?" Usually they want me to use a more modern one, and preferably Chrome, but here it might be worth trying a different and perhaps older one.

Neither of you have told us which browser you are using, nor its version, and when it was last updated, nor the operating system you are running it on, which might be useful. I suspect in this case that we might discover you are both using a browser that has been updated recently and has now set more secure defaults. Usually it's the web site that has updated and only now supports a newer browser. If we knew which it was, we could probably look and see how to disable its new enthusiasm.

I'm battling same problem, and thanks to WillInAberdeen for making a sensible sounding diagnosis.

I hope that the advice is not going to be to deliberately run an outdated browser with known security holes to access GBF?

@djh: it happens on firefox 102.12.0esr on Linux 3.10.0-1160.92.1.e17.x86_64 as well as on Chrome 118.0.5993.70 (Official Build) (arm64) running on a Macbook Air running Mac OS X Ventura 13.5.2 (22G91).

If I were able to edit comments, I would also ask DJH or anyone else who isn't having problems, to tell us what browser/version/os they are using.

I would ask if they had logged out and back in again today successfully, but warn that it might not work!

I have had no issues. (Famous last words) Windows 10 and MS edge.

Well some more weirdness - I now signed in the normal way, and was rejected when I deliberately used an incorrect password.. That doesn't fit what I said about passwords only being sent to https URLs. If I try an edit or posting, it signs me out.

63% of web browsing is done with chrome, so unfortunately I don't see much future for a forum that doesn't support it, or needs its default security measures to be turned off. Due respect to firefox (3%), and RIP to Netscape Navigator!

I had understood that chrome will no longer allow web forms to submit sensitive data (types such as passwords or credit card numbers) to non-https URLs.

Weirdly it seems that the non-https GBF address where passwords are sent for checking (http://www.greenbuildingforum.co.uk/newforum/people.php) was able to receive my incorrect password and reject it. So maybe something else is the problem..

I find the modern obsession with https everywhere rather frustrating. It does make sense for some things (like login forms), but a lot of the time it's pointless. E.g. it's extremely irritating to be told I can't download a PDF because it's 'insecure'. It's just a file, already public on the internet. I'd like a copy please, which doesn't need to be crypted and then decrypted just for transport. The risks of someone MITMing the transport and changing the file are low, and I'm just going to read it so if it said something slightly different (about retrofit) it wouldn't matter much, and if it said something completely different I'd notice (or the file would just be corrupt).

Firefox-esr 115.3.0esr is still working fine on the forum for both login and display, despite it bitching more than I would like about transport protocols sometimes.

The sign-in post link probably does need to change soon otherwise this resource will become unusable without digging out an older browser. (At least we can guarantee tat it will work in quite an old browser :-)
Given the complete lack of interest so far in updating it after previous threads, this may prove fatal. Has anyone managed to get a response from Keith? The site already has https working already so this is a trivial fix.

Posted By: WillInAberdeenIE it's looking like I might be about to have more time in my day, without GBF.

I'd be sorry to see you go. We don't always see things the same way, but I can generally appreciate your point of view, and it's usually well researched.

Many android users have our browser automatically apply updates to the latest version, after which there's no choice to go back to some earlier version, even if we were willing to (I'm not).

For me, it feels more important to have some control over what I run, but I accept there are other views. And android suffers from the same problem as chrome - too much google. I'd rather put my trust in apple instead.

Yes, Will-in-somewhere (!), please stay. Sending this (a) for that reason and (b) to see if I get locked out!!

Why doesn't the forum owner update the software? Is it no longer updated such that a port to another platform would be required?

Just checking forum plugins for wordpress. Doesn't look expensive... Could maybe port to my site if current host doesn't have time if that's possible in extremis. Don't want this community to disintegrate due to outdated platform.

https://addons.mozilla.org/en-GB/firefox/addon/greasemonkey/

I think the forum is effectively unsupported. The software in use has no easy migration path and the cost of custom migration is prohibitive. There was a suggestion it would migrate several years ago, but that never happened

At some point all will be lost as browsers are mandating HTTPS (they now often fail on internal http connections - I have a NAS that is unreachable via the browser which is daft!). It is the effect of dumbing down.

If these was to be a new forum, then the Discourse software (seen on the likes of Node-RED and HomeAssistant) is probably the best, but setting up and managing it is no small task.

Most of the 'free' systems such as Google Groups and Yahoo are slowly disappearing.

[edit]
Yes new forum was mooted in 2014/15. Search on 'forum' as a subject term for more info.

Several of us have offered to help over the years but Keith has never taken anybody up on it AFAIK.

Until the latest brouhaha about certain browsers knowing better than their users and forbidding connections, it hasn't really been a 'life or death' issue in any sense. It wouldn't be now except that some/many? people aren't willing to be flexible enough to use a browser that offers enough options (or perhaps to configure whatever browser they are using for this forum). I am, but I'm not willing to do other things like create a google account or a facebook account etc so I can understand their point to some extent.