Not connecting to yahoo mail

using Chrome Version 75.0.3770.100 and FF 67.0.4

X-notifer not connecting to yahoo mail. Working fine with gmail in both browsers

I have re-installed, double checked yahoo address and password without success


Try deleting history , cache , clear your browser , refresh Chrome  also refresh XN 42.13 

but everything is working for me and i am running Windows 10 OS  and latest Chrome & Firefox

so tried this and now even gmail is not working

Yes wondering what OS your running ? You didn't say and if your Gmails is not

working try logging into them one at time . Make sure your emails are sync to

your Chrome and Firefox browsers . Make sure they are all up to date 

Generally, it's not going to be an operating system problem and OS won't matter.
If it's not a problem created by the email provider changing their login (and a bunch of people would post complaints that  that provider's email wasn't being checked properly... and the XN developer would have to update the script)... 
...then it may be a conflict with another newly installed add-on, or...
...a 'prompt' during the login process from the email provider...
...or corruption in the XN install/reinstall or glitch in cache/cookies... or other browser settings.
- First thing I do...
Sometimes it's a 'prompt' from the email provider, where they ask to verify your security info again, or some other question that pops up that interferes with the login process. So I open a blank tab and go the email provider's webpage to log in manually and see if anything pops up that needs answering or OK'ing, whatever... take care of it, and log out. Then click X-Notifier's icon and click 'Check Now' to see if it works again for that account 
If not, then I'll click XN icon and click the account to see if it opens in a new tab - logged all the way into my inbox.  If not, then it may be a password problem. So I delete the account in X-Notifier and  then clear cache/cookies, then restart my browser - after which I redefine my acct in X-Notifier and Check Now.
If that doesn't work, I may uninstall XN, then clear cache/cookies, then restart browser... then reinstall XN, redefine -only- my problem account and test it.  It can be important to redefine the problem account from scratch and not first importing a backup. 
Sometimes, just to be persistent, I'll reinstall XN over the top of itself without uninstalling first.
Lastly, I can try setting up a new 'profile' in the Firefox browser ...or... 'adding a person' in the latest versions of chrome ...and then install a fresh XN to the new user profile/person, and define my problem account from scratch... this isolates/removes other possible old 'profile' or 'person' problems.
- And sometimes... the problem fixes itself if we wait a while... or there's a new browser update or a new XN release, etc.

However, it is because Yahoo has decided they will not support all Chromium browsers, only Chrome itself. I use SRWare Iron and can access Yahoo mail by answering Yes to continue usung Yahoo Basic Mail, but that extra question during login prevents X-Notifier from working.

after trying everything suggested...with no success, I switched to the newest version of yahoo.mail

yup, that did it.