The log file doesn't give any indication of cause for failure - just lists the plugins that have been scanned.
Update - just noticed the "Log HTTP requests" option in Settings. It does show the request, but doesn't show why the error is displayed.
I tried clearing my plugin list down, and just syncing CLAP. That worked.
I suspect the number of plugins I have is exceeding some web server limit somewhere. I do need a cleanout!
