It sounds like it doesn't like firefox on O365 online. Does another computer with IE or Edge do the same problem? I think O365 online works better with IE or Edge since those are more integrated to function better with O365.

WestEnd said

It sounds like it doesn't like firefox on O365 online. Does another computer with IE or Edge do the same problem? I think O365 online works better with IE or Edge since those are more integrated to function better with O365.

Yes, Office online works in Windows computers with Firefox 62.0.3, Chrome and Edge...so this issue is only with Linux version of Firefox. I would like to use FF on my linux laptop too, because bookmark syncing is so handy, but seems to be that I need to use Chrome instead

One of the challenges we face on Mozilla Support is that different distributions may tweak settings, bundle extensions, or even remove stuff so that your Firefox behaves differently from the one available on

https://www.mozilla.org/firefox/all/

If you prefer the one that installs through your distribution, could you also check whether they have a support site that might have info on this question?

If a site is generally known to work in Firefox, these are standard suggestions to try when it stops working normally:

Double-check content blockers: Firefox's Tracking Protection feature and extensions that counter ads and tracking may break websites that weren't built to operate normally without the blocked components.

Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the Tracking Protection feature in this article: What happened to Tracking Protection?.

Extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site.

Cache and Cookies: When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "Clear Cookies and Site Data"
• (menu bar) Tools > Page Info > Security > "Clear Cookies and Site Data"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "Clear Cookies and Site Data" button

In the dialog that opens, you will see one or more matches to the current address so you can remove the site's cookies individually without affecting other sites.

Then try reloading the page. Does that help?

(3) Allow third party cookies

See: Websites say cookies are blocked - Unblock them

Testing in Firefox's Safe Mode: In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Hi Jscher2000, Thank you for you comprehensive explanation. It must be something in this Manjaro bundle since I updated and tested exact the same Firefox version in Ubuntu 18.04.1 LTS and there O365 app do work just fine! I throw the question also to the Manjaro forum, but no replies so far.

I don't have any content blockers installed, in fact not any extensions or plugins installed at all. No shield icon next to the lock symbol. Cleared cache and cookies; reloaded page, no change.

Tested the safe mode, no change.

The page reload / stop button is flashing like a crazy and there is text bounding at left bottom corner: waiting for login.msoy-my.sharepoint.com -> Sending request to login.micosoftonline.com

Maby I just give up and install "clean" version of Firefox :/

Are third party cookies allowed? Cycling to the login page implies some kind of cross-site authentication issue.

jscher2000 said

Are third party cookies allowed? Cycling to the login page implies some kind of cross-site authentication issue.

Yes they are. I've tried to chek that every settings are exact the same on Firefox@Manjaro than on my Ubuntu and Windows machines.