I really think there is something to this, William. It messed with my contacts and seemed to be a disconnect or bug there. In my case, deleting contact data, Facebook, calendar all did NOT work. So I went through my phone's app list purging unnecessary apps.
But I think I found the culprit in my case: Facebook Messenger. It recently decided that it was smart enough to import all my SMS messages into messenger as if it was going to be my default messenging app. So I killed it and voila! the notices went away. I did try to reinstall it only to have the error reoccur. So screw Facebook messenger. I never liked you anyways.
So I thought I had this bug zapped, but it was not to be. My error would crash only my contacts and things my contacts accessed, such as the messaging and phone app. Kind of a problem if a device can't perform its two primary functions, call and text. If I needed to make a call, I'd have to dial it manually instead of from contacts. Also, "OK Google Now, call wife" etc. still worked. So I used that for a bit.
But it got so frustrating, I just bit the bullet and decided to factory reset my phone. I looked into backup options so I wouldn't lose everything. There are no real good solutions without rooting, which I have NOT done to my phone. If you have rooted, Titanium Backup is supposed to save all your info, apps, appdata, etc. So I screenshot my apps, printed them off, I did back up my messages and phone logs via CM Backup and Super Backup apps.
Surprisingly, after factory reset, it automatically restored about 90% of my apps automatically, including some of the app data such as AlarmDroid AND my alarm times. That was a nice bonus. I had to manually install a few apps, games and entertainment mostly. And most importantly NO process.android.acore messages. The automatic recovery may be linked to my carrier or one of the numerous manufacturer backup apps that are installed. Not sure but it was not so bad.
I backup up my messages and phone logs via the two apps above. Worked fine. Installed the missing apps one at a time. Then I installed a Reddit browsing app I used frequently before the crash, RedditIsFun or RIF. As soon as it installed, process.android.acore returned. I uninstalled it and the couldn't replicate the error. Reinstalled and immediately returned.
Tl;dr Factory reset wasn't so bad. Error reappeared after installing Reddit is Fun app. It may return, but I'm good for now.
Motorola XT 1080- Droid Maxx
Android 4.4.4
Carrier: Verizon