After a power outage, the vCenter filesystem is inconsistent like described here: https://knowledge.broadcom.com/external/article/338155/manually-running-fsck-on-vcenter-server.html
If the file inconsistency cannot be resolved with the above KB article, you may consider deploying a new vCenter.
vCenter 6.7
vCenter 7.x
vCenter 8.x
1. Download the vCenter installer of the required version from the Broadcom portal: https://support.broadcom.com/
2. Follow the steps in the following document to complete stage 1 of the installation: https://techdocs.broadcom.com/us/en/vmware-cis/vsphere/vsphere/7-0/vcenter-server-installation-and-setup-7-0/deploying-the-vcenter-server-appliance/gui-deployment-of-the-vcsa-and-psc-appliance/deploy-the-vcsa-embedded-architecture/stage-1-deploy-the-ova-of-vcsa-with-an-enbedded-psc.html
3. Follow the steps in the following document to complete stage 2 of the installation: https://techdocs.broadcom.com/us/en/vmware-cis/vsphere/vsphere/6-7/vcenter-server-installation-and-setup-6-7/deploying-the-vcenter-server-appliance-vCenterServerInstallationAndSetup/gui-deployment-of-the-vcsa-and-psc-appliance-vCenterServerInstallationAndSetup/deploy-the-vcsa-embedded-architecture-vCenterServerInstallationAndSetup/stage-2-set-up-the-vcsa-with-an-embedded-psc-vCenterServerInstallationAndSetup.html