WTF!

Does anyone know what can fix this?

Looks like corrupted user json. There should be a backup folder. U can stop copy from there otherwise you need to restore json from your backup version

This does appear to be a corrupted or missing user settings.json file. I recommend you stop the SmarterMail system service (and wait for it to drop out of Task Manager) then restore a good backup copy from that user's Archived Data folder. Root causes for this can vary quite a bit so if you need a hand tracking down the culprit please don't hesitate to submit a ticket with us. 

This happens to a user or two on my build every few months.  I sometimes just change the pword and then change it back to what it was.  If using AD come off the AD, save, and then put it back.

Kyle---Are you able to track this down if it occurs in the future?  Just open a ticket?

We can Mike! Usually this is caused by one of a couple of culprits: 

The first will obviously show up as an error in the Event Viewer in Windows, as will disk or disk controller errors. The second possibility can be confirmed using Process Monitor from Microsoft (https://learn.microsoft.com/en-us/sysinternals/downloads/procmon) which can be filtered to INCLUDE any access to files/folders in the C:\SmarterMail\Domains folder and its subfolders and EXCLUDE any access by MailService.exe, W3WP.exe, Explorer.exe, etc using the Filter>Filter menu. With that in place you should see only things that are touching our files outside of SmarterMail and IIS. If you submit a ticket when it happens though we're happy to help take a look!

k--thanks, will investigate as you suggest next time it come up.

We've had some issue with corrupted account JSON files in the past. Here's a powershell one-liner we use to check for empty (i.e corrupted) JSON files:

In build 8776, we have experienced two occasions where a user account was not usable from Webmail.   On the second incident, we were able to determine that the account was still usable from Outlook/MAPI and CellPhone/EAS.   In both cases, corruption was not the issue and a system reboot solved the problem.   We were also able to prove the folder was not corrupt by renaming the account while it was locked out.   Once the name was changed, the account was usable.   Support has been notified but we do not yet have a smoking gun.  Because a reboot fixes the problem, the issue appears to be in-memory corruption.

FYI - Build 8776 there are problems authenticating with AD.  Users cannot log in when authenticating through AD.  I updated to 8776 this weekend and got burned on this.  Tried to roll back to my previous build but the problem remained.  One emergency ticket and $350 later through no fault of my own...

Yeah Mike... been there, done that. Kind of annoying....

Tony did a great job and was very responsive so I'm thankful for that.  

I also understand that it's hard to ascribe fault---is it the OS or your set up or the software itself?  A function that was working fine and then just breaks on an update seems more black and white to me.

Then that gets you to when is it best to update?  Naturally when there is the most downtime to allow for recovery in the case of problems.  For me that's the weekend.

While I back up my build I don't currently have enough space on the host to create a checkpoint.  With this experience I'll focus on fixing that fault point.

My business makes a physical object that I sell to other businesses.  We mess up on occasion as all companies do.  When we make mistakes we pay freight back and forth and replace the product.  But I don't pay any downtime incurred due to the fault of my product.

I don't know what the standard is in the world of software.

Then I weigh it against $350 which as a business isn't that much to me in the grand scheme of things.

I would say that checkpoints are worth their weight in gold but seeing how they don't weight anything, I guess they're worth far more than their weight in gold!

I agree.  I had an issue with my checkpoints which I resolved this morning so I'm good to go moving forward.