This shows up intermittently in the recurring charge job. I think it might be related to the one where we are trying to send a recurring failure notification to a bad email address.
2021-04-29 00:36:21,291 ERROR WD civicrm: $Fatal Error Details = Array [error]
2021-04-29 00:36:21,291 ERROR (
2021-04-29 00:36:21,291 ERROR [callback] => Array
2021-04-29 00:36:21,291 ERROR (
2021-04-29 00:36:21,291 ERROR [0] => CRM_Core_Error
2021-04-29 00:36:21,291 ERROR [1] => exceptionHandler
2021-04-29 00:36:21,292 ERROR )
2021-04-29 00:36:21,292 ERROR
2021-04-29 00:36:21,292 ERROR [code] =>
2021-04-29 00:36:21,292 ERROR [message] => Failed to write to socket: unknown error
2021-04-29 00:36:21,292 ERROR [mode] => 16
2021-04-29 00:36:21,292 ERROR [debug_info] =>
2021-04-29 00:36:21,292 ERROR [type] => PEAR_Error
2021-04-29 00:36:21,292 ERROR [user_info] =>
2021-04-29 00:36:21,292 ERROR [to_string] => [pear_error: message="Failed to write to socket:
2021-04-29 00:36:21,292 ERROR unknown error" code=0 mode=callback
2021-04-29 00:36:21,292 ERROR callback=CRM_Core_Error::exceptionHandler prefix="" info=""]
2021-04-29 00:36:21,292 ERROR )
2021-04-29 00:36:21,292 ERROR