As a supreme irony, I had this exact issue for most of the night last night (minus the error message). It turned out to be a problem with a new, unreleased, version of UpgradeMODX. When I took UGM off the dashboard, everything was fine. One clue was that if I bypassed the dashboard I could go directly to editing a resource after logging in. The Manager worked fine as long as I avoided the dashboard.
It reminded me of a similar problem I’d seen before. If something goes wrong while MODX is pulling the News and Security feeds, it seems to leave cURL in an unusable state. The next widget that tries to use it crashes the dashboard. The problem was intermittent, like yours. Moving the UpgradeMODX widget to the top of the dashboard prevented the issue, which may or may not be fixed.
I should also mention that a version of UpgradeMODX throws an
Things to Try
My first guess on the cause of your issue would be a dashboard widget, especially if there is a dashboard widget that uses Discuss or Rampart, or uses the internet to grab anything off site.
It’s easy to remove widgets from a dashboard, and it doesn’t delete them, it just keeps them from executing. The first thing I’d try is just turning off the News and Security feeds (in System Settings, search for
feed and you’ll see the settings). If that doesn’t work, I’d try moving UpgradeMODX to the top of the dashboard, and if that fails, removing it from the dashboard.
My second guess would be a problem with a plugin attached to a Manager login event.