When viewing a page there is a red flare with an error that states:
"We're Sorry! An unexpected error has occurred. We have recorded this error and will begin to investigate it. In the meantime, if you would like to speak with our Support Team, Please reference the information below:java.lang.NullPointerException"
Typically the error includes additional information such as a date and timezone
One cause is that the filter or view being used has become corrupted or somehow conflicts. While this doesn't happen very often it can be caused by a wide variety of issues.
You can often resolve the error by removing the corrupted/conflicted view. You may also need to clear your cache.