I'm not aware of any issues affecting Firefox 45.9.0esr, which I assume is what you run since your browser identified itself generically as Firefox 45 and that would be the most up-to-date version.

For issues affecting Firefox 48 and later, see: https://support.mozilla.org/questions/1166878#answer-984472

At this point, for Firefox 45, I can only suggest "the usual":

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

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. If you do not see the number going down on the page, you can reload it using Ctrl+r to check progress.

(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 > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button

In the dialog that opens, the current site should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually.

Then try reloading the page. Does that help?

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

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

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

and OK the restart.

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

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

If you meant directly pasting into a message rather than using the attach a file feature, that's different. Sites need to use a script to translate the pasted data into message content. There might have been a change recently on Microsoft's side because a user of the current version of Firefox also reported a problem:

https://support.mozilla.org/questions/1167811

I have same problem in this case until now, the problem not solving. I think Firefox must work hard for make the better browser.

Hi berrit, what method are you using to attach a screenshot to a message you are composing in Outlook (online)? Where is the problem arising?