Blank admin screen and desktop app after upgrade to 6.6

After upgrading from 5.37 to 6.6.1, I can’t pull up the administration screen or the macOS desktop app. Mobile seems to work just fine. Log shows plugin failures.

Observed behavior
The log shows the database schema upgraded from 5.37.0 to 6.4 with no trouble. However, the following appear after:

Failed to extract plugin with path /opt/mattermost/prepackaged_plugins/mattermost-plugin-apps-v1.0.1-linux-amd64.tar.gz: extractPlugin: An error occurred extracting the plugin bundle., unexpected EOF"}


{"level":"warn","msg":"Health check failed for plugin","caller":"plugin/health_check.go:59","id":"com.mattermost.nps","error":"plugin RPC connection is not responding"}
{"level":"error","msg":"RPC call OnDeactivate to plugin failed.","caller":"plugin/client_rpc_generated.go:33","plugin_id":"com.mattermost.nps","error":"connection is shut down"}
{"level":"warn","msg":"error closing client during Kill","caller":"plugin/hclog_adapter.go:70","plugin_id":"com.mattermost.nps","wrapped_extras":"errconnection is shut down"}
{"level":"warn","msg":"plugin failed to exit gracefully","caller":"plugin/hclog_adapter.go:72","plugin_id":"com.mattermost.nps"}

I made no changes to the plugins during the upgrade and I think I’m running a fairly stock server (at least I don’t remember installing any other plugins).

Suggestions on what to do next?