Obsah

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Slack is a platform made for teams to easily communicate in channels and queries (private messages). It has apps for mobile platforms (Android, Windows Phone, iOS) and on desktops you have two options. Either use their app which is really only a website wrapper, or use the website interface in a browser. Which is what I do.

The support for browsers is not bad, they support, to my knowledge, Firefox, Chrome, Edge and Safari in the newest versions. However, I use Pale Moon and that is officially a unsupported browser, so the web app will tell you something like "sorry, we don’t support your browser, use some other" when you try to load Slack in Pale Moon. So, for some time I had next to my Pale Moon also permanently opened Firefox with Slack loaded, but that’s not a very convenient setup, so I searched for a way to fool Slack and try using it in Pale Moon. And the way I found thanks to this forum thread on Pale Moon website is very easy and Slack works on Pale Moon like a charm so far. (Tested both on Ubuntu 16.04 and Windows 10 with Pale Moon 27.4.2 both 32bit and 64bit).

So, how to fool Slack to load in Pale Moon?

Do the following:

1. Open a new tab and type about:config to URL bar and hit Enter key (or whatever is your equivalent on Mac) to go there. You may be presented with a warning that it’s a config interface for advanced users, confirm that you understand the risks and want to go there. (The risks are none if you won’t do anything else there than what I’m telling you here to do. But, you’ve been warned.)
2. Right click somewhere in the page and select "New" -> "String".
3. A small window will pop up with a prompt saying "Enter the preference name" — insert following string there: general.useragent.override.slack.com and hit OK.
4. Next window will appear named "Enter string value". Enter following string there: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.9) Gecko/20100101 Firefox/52.9 and hit OK.

And you’re done. Open a new tab and try loading Slack, it should work without a problem now.

What did we do?

We’re telling Pale Moon to untruthfully report to Slack that it’s a rather different browser (basically some fairly new version of Firefox on Windows, it seems) which is supported by Slack. That way Slack won’t refuse to load in Pale Moon.

A future note: obviously, in the value of the string, there’s a version of the browser we’re making Pale Moon pretend to be. Thus there’s a possibility that in future this value will have to be updated so we would pretend we’re using a newer version of Firefox, because the version used in the value here will not be supported anymore. Try finding out the right value the same way I did it — copy it from some other setting in the about:config page.

If found out this workaround doesn’t work for you for some reason, you can report it here in comments. Even better would be if you’d also shared a solution in case you’d find one, so others (maybe me in a future) have some other way to solve this problem. Thanks!