Ubuntu desktop-client connecting intermitently - Nextcloud 11

I’m running nextcloud 11 on an ubuntu 16.04 server. I have an ubuntu 16.04 machine that was connecting reliably to the server from some weeks. Now we have a problem with connectivity for this computer. Other computers in the office connect to the cloud fine. This system stopped today. Can someone let me know what this error message means:

Uncaught Error: Access to undeclared static property: OC\Files\Filesystem::$normalizedPathCache in /var/www/nextcloud/lib/private/Files/Filesystem.php:806 Stack trace: #0 /var/www/nextcloud/lib/private/Files/View.php(2018): OC\Files\Filesystem::normalizePath(’/jillgregori/fi…’) #1 /var/www/nextcloud/lib/private/Files/View.php(1156): OC\Files\View->unlockFile(’/01-APR/Marketi…’, 1) #2 [internal function]: OC\Files\View->OC\Files{closure}() #3 /var/www/nextcloud/3rdparty/icewind/streams/src/CallbackWrapper.php(109): call_user_func(Object(Closure)) #4 [internal function]: Icewind\Streams\CallbackWrapper->stream_close() #5 {main} thrown at /var/www/nextcloud/lib/private/Files/Filesystem.php#806