We can't view the main groups page -- a popup error appears and no groups are shown. The error is:
DataTables warning: table id=DataTables_Table_0 -
Invalid JSON response. For more information about
this error, please see http://datatables.net/tn/1
In this case, turning on logging (civicrm/admin/setting/misc?reset=1) and looking in the CiviCRM log reveals a fatal error related to mapping and geocoding:
Proximity searching requires you to set a valid geocoding provider
Somebody had tried to set up a proximity group based on zip codes, but the mapping and geocoding settings had not been configured. Configuring the geocoding (civicrm/admin/setting/mapping?reset=1) to use Google as the provider fixed the issue.
