Permission error on session_start() after 3.5 upgrade On my dev box, I have php/nginx running as 'jim'. I've followed the suggestions on permissions in the install docs. (744 since php is running as 'jim')
I'm getting this error...
PHP Warning – yii\base\ErrorException

session_start(): open(/var/lib/php/sessions/sess_a693hln410j5992m23otjnc7nf, O_RDWR) failed: Permission denied (13)

and my folder perms look like this...
-rwxrw-r--   1 jim jim    618 Aug 10 14:21 composer.json
-rwxrw-r--   1 jim jim 216281 Aug 24 11:29 composer.lock
drwxrwxr-x   4 jim jim   4096 Aug 18 11:55 config
-rwxrwxr-x   1 jim jim    655 Jun 23 17:36 craft
-rw-rw-r--   1 jim jim    330 Jun 23 17:36 craft.bat
-rw-rw-r--   1 jim jim   1813 Jul 24 15:54 gruntfile.js
-rw-rw-r--   1 jim jim   1037 Jul  7 18:33 gulpfile.js
-rw-rw-r--   1 jim jim    982 Jul  2 17:19 layout.html
drwxrwxr-x   2 jim jim   4096 Aug 17 15:14 logs
drwxrwxr-x   2 jim jim   4096 Jun 23 17:36 modules
drwxrwxr-x 683 jim jim  24576 Jul 11 15:28 node_modules
-rw-rw-r--   1 jim jim    420 Jul 11 15:28 package.json
-rw-rw-r--   1 jim jim 356363 Jul 11 15:28 package-lock.json
drwxrwxr--   7 jim jim   4096 Jul 16 08:38 storage
drwxrwxr-x  12 jim jim   4096 Aug  6 10:07 templates
drwxrwxr--  56 jim jim   4096 Aug 24 11:29 vendor
drwxrwxr-x   5 jim jim   4096 Jul 20 23:36 web

I've also tried opening up the following files/directories with 777, but still get the error:
.env
composer.json
composer.lock
config/license.key
config/project/*
storage/*
vendor/*
web/cpresources/*
Easy fix. Removed all session data which had www-data:www-data ownership.