It's not as convenient as the Profile Switcher add-on, but profiles can be launched from Help/Troubleshooting, about:profiles.

For an XNote replacement, see QNote.

Thank you....

(#1) I need a profile switcher that will keep multiple profiles open at the same time. Hopefully what you have recommended can serve that need.

(#2) I have upwards of 5000 x-notes that are absolutely integral to my archival process. So moving to another add-on will not do. The X-note site seems to indicate that they have a test version ready or almost ready and that they are working on updating z-note for 78.4.

Aside: There really needs to be a better system / relationship between these add-ons and TB. It puts me in total crisis every year or so, and not ever updating TB is also unsustainable.

You have helped me greatly in the past (I cannot ever forget your goat profile photo - please do not ever change it), most recently in Feb or so of this year when this same thing happened: profile switcher and x-notes. But that time both were ultimately compatible with the upgrade, whereas this time it does not seem like I have fared as well, unfortunately.

I can have multiple profiles open at the same time, launching them from about:profiles.

I think Qnote has an option to import Xnote++ content:

https://addons.thunderbird.net/en-us/thunderbird/addon/qnote/reviews/1163539/

Thanks will look into both issues by following the leads you have kindly given....

I can have multiple profiles open at the same time, launching them from about:profiles.

How do I do that??? I am not sure how to launch them that way. Is there a step by step guideline somewhere?

From about:profiles, click 'Launch profile' to open it in a separate window.

Where is this ==> "about:profiles"

How can I find that spot?

Under Help/Troubleshooting Information (see picture).

How wonderful - that worked perfectly - I can easily live with this system!! That add-on issue (profile switcher) is SOLVED!!

It is getting late (EST) so I may or may not be able to investigate the Qnote before bed - but will let you know how it goes...

Thank you again - as always!!!

Here is how to get X-note on TB 78.4.

(a) Download the file at the below link:

https://addons.thunderbird.net/thunderbird/downloads/file/1017761/xnote-3.0.0-tb.xpi

(b) Then do a manual install which is essentially 1-click of a button:

See the screenshot of the gear drop down menu from the Add-ons tab: "Install Add-on From File..."