I can't install any plugins on QGIS since updating to 2.18 (I am running High Sierra). I am connected to the QGIS Plugin Repository yet receive the error message:
Plugin installation failed:Failed to unzip the plugin package. Probably it's broken or missing from the repository. You may also want to make sure that you have write permission to the plugin directory.
I have downloaded the plugin (openlayers) and extracted to the .qgis2/python/plugins/ directory but receive the error message: No QGIS plugins found. I am not using a proxy so don't think that is the error.