Horde is a popular webmail software and comes installed with cPanel. We had a situation where accounts were moved across servers using WHM on a cPanel server. After the upgrade customers reported that in their horde address book entries, they see NULL with the names of their contacts.
We have removed the names for privacy from the screen shot above. We investigated the issue and found that the table turba_objects in horde database is holding literal NULL text instead of NULL datatype. We had to run multiple SQL queries like the following to get all the records updated:
UPDATE `turba_objects` set object_lastname=NULL WHERE object_lastname='NULL'
Once all the columns were updated, there were no more NULL text displaying in customer’s contacts. It looks like when cPanel/WHM did the data transfer across servers, it somehow enclosed the NULL in quotes making them literal text.