Since 8.1.0 ownCloud is fully unsupported on windows. This is since ever and the first release of 8.1.0. Additionally 8.0.0 was also already unsupported [1] on windows.
There is currently no way to get ownCloud to work on windows as oC 8.0.0 is unsupported since a few months and won't receive any updates or security fixed. Please move your installation to a linux based host and install a fresh ownCloud 9.1.4 is you want to continue using ownCloud.
[1]