Upgraded to Emacs 28.1. Treemacs doesn't show upon starting emacs anymore.

This is in my config file (init.el) `(use-package treemacs` `:ensure t` `:demand t` `:hook (after-init . treemacs)` `:config` `(treemacs)` `)`

Random: blow away any eln-cache directory (native compile from before) and any elc files (bytecompiled elisp) in your .emacs.d .. I was getting a lot of crashes and oddities until I did that. There are also some settings .. seems like emacs when seeing a newer .el and an older .elc will use the older file (instead of compiling the newer one - seems insane). So blowing away just to make sure fixed up 28.1 for me There are some settings to package managers to avoid tthat, and packages that force recompiles and sich.. who knew

Be aware of (setq load-prefer-newer t)

I just use this in my .emacs, works fine. (treemacs) then I change the toggles manually when they annoy me too much.

Update treemacs. Treemacs used the deprecated `make-obsolete` interface in versions [before January 2021](https://github.com/Alexander-Miller/treemacs/commit/55631977ab3b7ca9f1527d9480c72145357521f2); as Emacs 28 made the new interface mandatory (the old one had been deprecated since like Emacs 23), older versions no longer work in Emacs 28. Another tip: check the `*Warnings*` buffer if some package doesn't seem to be loading properly, if you're using use-package. Chances are it emitted an error while loading, but use-package caught the error so that your Emacs can still start.

> blow away any eln-cache directory (native compile from before) This definitely *shouldn't* change things. Native-compiled .eln files are hashed not only by the elisp content, but also by the build of Emacs -- a newly compiled 28.1 will completely ignore pre-existing .eln files for previous builds. Of course, for that same reason, you should probably purge the old ones because there's no reason to keep them; but that's only to reclaim the disk space -- doing so shouldn't affect the behaviour in any way.

Yep, agreed; pretty sure the eln-cache wasn't part of the fix for me .. pretty sure it was the elc wiping that fixed my install up. I did both steps at once, while trying to debug wtf was going on :)