Try disabling these settings on /admin/site_settings:

• Use simple cache
• Use system cache

Then go back to Dashboard and run Upgrade.

If everything worked, change the caching settings back and run Upgrade again.

If this doesn't help and/or you get a message about the upgrade process being blocked, then check the permissions for /data directory on your server.

Permissions should always be set for the server, i.e. www-data, http2 etc

If you run something in the console as root, e.g. php elgg-cli or copy/create something in /data directory, then you may have such problems.

Always change the permissions back with this command:

chown -R www-data:www-data /path-to-your-data/

Learn this also: 1, 2, 3

Tip: use this plugin if you need to control files in your /dataroot directory.

Thanks for the quick reply, Nikolai!

Unfortunately, my problem persists.

Doing the .. disable-cache, upgrade, enable-cache, upgrade .. all seemed to succeed (no errors), but the CSS is still missing. The permissions on my data directory look fine (and files are being written in there). I haven’t really done anything at the command line or made any changes other than the few changes in the Admin / Settings. This is a very vanilla installation.

I reviewed the other links you provided, and none really apply to my situation.

My “production” installation still seems to be working (although I haven’t touched the cache settings). I’m wondering if something has just become corrupted in the “dev” installation. I think I’ll flatten it and reinstall, and then see if I can reproduce the problem. If I can’t reproduce the issue, I’ll just chalk it off to some random corruption. Will let you know how it all goes.

Thanks!

https://github.com/ColdTrick/any_home

Excelent @rivervanrain 

Thanks

Welcome to Elgg!

You shouldn't set read/write permissions on the root installed folder for the server user (i.e. www-data, httpd etc) but only local users . 

Usually we create another user without root permissions to change, read the root installed folder on his behalf.

chown -R developer:developer /var/www/elgg/

The exception is the data folder.

I also recommend you set chmod 444 on the settings.php file after you've made all the changes you want:

chmod 444 /var/www/elgg/elgg-config/settings.php

Thanks! This helps a lot!