I tried to migrate the users, system settings, point property templates, global scripts, excel report templates, and graphical views from Mango ES serial number 3386 to serial number 3396 using the Configuration Import/Export utility in the new GUI. The unit in question, 3396, seemed to be working okay before this. After importing the JSON and restarting, it's now unusable via the web interface. It boots showing the debug output on the web page, then when it tries to launch the GUI, the spinning loading ring just stays there. When the page is refreshed, the system crashes and it starts again.
I also cannot access the system over SSH. I plugged a monitor in and was able to delete the H2 database and clear the jsp folder so that they can be repopulated. The problem persists.
I'm trying to figure out how to recover this unit. I cannot provide any detailed info from the web GUI since I can't get to it, but I can provide anything accessible over local CLI. Firmware is V3_XU4_3.2.1_09_06_17_R. Accessing the device over Firefox 56.0.1 on Windows 10.