I stumbled upon a strange Batch Apex issue today. My batch job was going well in few SFDC orgs; after deploying the same to a new org it stopped working completely. I just see, “First error: Attempt to de-reference a null object” in debug and apex logs.  After adding a lot of debug statements in both start() and execute() method, I found that “execute(Database.BatchableContext BC, List<Sobject> scope)” is never called after creating QueryLocator in start().

Read More: https://abhinav.fyi/batch-apex-first-error-attempt-to-de-reference-a-null-object/