Fatal errors after upgrade from Joomla 3

Hiya there, I hope all is well

I've finally got around to upgrading, its a bit of a mess because the theme I used was discontinued, so may be elements left over and interfering? In any case I installed a new theme and can't get sermonspeaker to load, when I click on it from admin side I get a error that states:
Warning: require_once(/var/www/site/administrator/components/com_sermonspeaker/vendor/autoload.php): failed to open stream: No such file or directory in /var/www/site/administrator/components/com_sermonspeaker/sermonspeaker.php on line 27

Any ideas?

So I can see its true there is no file there, administrator/components/com_sermonspeaker/vendor/autoload.php and not even a directory called vendor.
ie. $ ls administrator/components/com_sermonspeaker/
access.xml config.xml controller.php controllers helpers language models script.php sermonspeaker.php sermonspeaker.xml sql tables views

But don't know why its trying to load it, I see a mix of files there some from march 30 2022, some from 2019?
* correction: I saw folders not files from 2019, obviously not recreated when updated.
** I checked extension upgrades and found a few sermon related ones not updated, after a few attempts one did, but I still get this message for two of them.
Update: Could not open update site #102 "Bible Verse Reftagger Update", URL: www.graphicaholic.com/downloads/FaithLif...ereftaggermodule.xml
Update: Could not open update site #112 "SermonSpeaker.net", URL: www.sermonspeaker.net/update/plg_sermonspeaker_pixelout.xml
I uninstalled bibleversetrftagger but it didn't help,

Sounds like Joomla didn't completely copy the files. You're also missing the folder "presets" there. Try to install SermonSpeaker 6.0.2 again over the existing installation.
The files definitively are in the zipfile and are also referenced in the install XML file.

The "Bible Verse Reftagger" isn't an extension from me.
The Pixelout one is no longer available. It was a Flash-based player and Flash doesn't really work anymore in modern browsers.

That worked! Amazing, I didn't realise you can install again. I considered uninstalling then reinstalling but was worried I would loose content and categories etc if I did that.

It's all working now I just need to put some time into cleaning up content and organising it with the new options that came in 6.x

Thank you again Thomas for such a fantastic tool.

Reinstalling should work with any Joomla extension. Joomla detects itself if it is a fresh install or an "update" and will do the necessary things. In our case here it just copies all files again.

If you uninstall, you would indeed loose the data as the SermonSpeaker database tables and categories and such things are deleted as well.