Please can you investigate what is "System.NullPointerException" error which shows in the Error Log Subject?
There is a processor that runs every night, when the processor ran it encountered with a null value and hence the error logged. When it has a program area like this (a number 7079...), that means it's from an Apex Job.
You may see some more descriptions in the setup > monitor > apex jobs. Look for something that ran at the same date/time the error log was created. That would at least give the Apex Batch Processor name that caused the issue. Please check if you have updated latest release note version.