Can anybody explain what the following console error message means:

ERROR: logic relay [name of logic relay] has been trigger but is awaiting refire. OUTPUTS WILL NOT BE FIRED!!!

I've googled hammer portal "awaiting refire" but, surprisingly, only get 6 results returned, none of which explain what the error means.

Basically it's a feature of relays to prevent them being retriggered quickly. Whenever it is triggered, it ignores further Trigger inputs until 0.01s after the last OnTrigger output fires. The "Enable fast retrigger" flag disables this behaviour, if you want to trigger it quickly.