Calendar page empty after upgrade to 9.0.8

[tsmr2015]

Please help us by providing the following info. Before posting please also check the pinned "Known issues" threads and make sure that you're running the latest available version for your oC release: https://owncloud.org/changelog/

Steps to reproduce
1. Upgrade to 8.2.10
2. Upgrade to 9.0.8

Expected behaviour
Calendar should work

Actual behaviour
Calendar does not work correctly, the page is displayed inside Owncloud but completely empty.
See screenshot here: http://imgur.com/a/YmDSC
WebDAV however keeps working without issues.

Server configuration
Operating system: Linux
Web server: Apache 2.4.10
Database: Mysql 5.5.53
PHP version: 5.6.30+dfsg-0+deb8u1
ownCloud version (see ownCloud admin page): 9.0.8
Updated from an older ownCloud or fresh install: update
Special configuration (external storage, external authentication, reverse proxy, server-side-encryption):

ownCloud log (data/owncloud.log)

Please paste possible errors in the following code block, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808 for more info

Integrity status for oC9+

Integrity checker has been disabled. Integrity cannot be verified.

[tflidd]

Can you enable the sharing API on your admin page? Also the share files app.

Issue: Calendar not showing at all [datepickerFilter]

[tsmr2015]

Is this really necessary?
I've had issues with the sharing api in previous OC versions.
Furthermore it isn't a feature that I want or need.

[anon81984126]

If the calendar items are not showing up without the sharing api but with an enabled sharing api then it is (obviously) necessary.

[tsmr2015]

Thanks, I'll just wait for it to be fixed then.

[anon81984126]

Waiting won't fix anything . And it could be possible that nothing needs to be fixed if the Share API is required / mandatory for the calendar app.

[tflidd]

There should be a maintainer for owncloud but he never really started:

Calendar App got a new Maintainer

After the announcement at the mailinglist that the calendar app is unmaintained: http://owncloud.10557.n7.nabble.com/ownCloud-calendar-app-unmaintained-td17676.html a new maintainer was found and the development of the ownCloud calendar is ongoing again: Just to be clear on what is going on here from an owncloud perspective: - @felixheidecke will maintain calendar - in a very first step we will sync up the repos - after that we will continue to develop this app - nc is welcome to grab cha…

[tsmr2015]

It doesn't make any sense.
I don't want nor need the share API (this is a private system that requires vpn access) and each OC feature should be able to live independently from others

[anon81984126]

Unfortunately, we users in here can't do anything about this . Even if it doesn't make any sense to you.

So keep an eye on the linked issue above if there is anything which needs to be fixed for the calendar app or if you just need to enable the Share-API for the calendar app to work.