My users log in via AD accounts. All but 2 can log in

Both of the users that cannot log in used to be able to and recently cannot. After successful authentication, they are met with:

Internal Server Error

The server was unable to complete your request.

If this happens again, please send the technical details below to the server administrator.

More details can be found in the server log.

  • Remote Address: originating IP
  • Request ID: XBE4xbad84ezoEgjAruJVgAAAAY

In the nextcloud.log I see:

{“reqId”:“XBE6Wq5za1nKuEL8bKnbnwAAAAA”,“level”:3,“time”:“2018-12-12T16:42:02+00:00”,“remoteAddr”:“”,“user”:“lskywalker”,“app”:“PHP”,“method”:“GET”,“url”:"/nextcloud/index.php/apps/files/",“message”:"You are using a fallback

implementation of the intl extension. Installing the native one is highly recommended instead. at /var/www/nextcloud/3rdparty/patchwork/utf8/src/Patchwork/Utf8/Bootup/intl.php#18",“userAgent”:"Mozilla/5.0 (Macintosh; Intel Mac O

S X 10_14_2) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.2 Safari/605.1.15",“version”:“”}

Nextcloud version: 14.0.4
Operating system and version: CentOS Linux release 7.6.1810 (Core)
Apache or nginx version: httpd-2.4.6-88.el7.centos.x86_64
PHP version : PHP 7.1.24