updates not working- wpmuv plugins - other updates being blocked for other plugins also

this actually affects all sites I have and wpmuv plugins are the common thing on all of them - when we try to update defender - it results in an error - Could not copy file. wp-defender/interface/class-wd-module-abstract.php

we tried via wp dashboard, via wpmuv dashboard and it wont work; also other plugins are not updating either; our tool bar in choc diet shows 3 updates which donot show on the updates page so we think this is an issue that calso could be related to the wpmuv suite/dashboard...

we attempted to uninstall and delete wpmuv plugins from the site to test that thery - but it won't allow us to delete or uninstall any of the wpmuv plugins - can you help?