On some devices, some files may become corrupt over time. The main reasons we have identified seem to be around heavy use of the device and automatic updates.
We are unfortunately unable to prevent this file system corruption from happening, but we can help you fix your device and nurse it back to health.
The most common symptom is that the Administration UI starts failing on some pages (potentially all of them).
The typical error message that gets displayed instead of the page looks lie this:
/usr/lib/lua/luci/dispatcher.lua:330: Access Violation
The page at 'admin/invizbox/privacy_mode/' has no parent node so the access to this location has been denied.
This is a software bug, please report this message at https://github.com/openwrt/luci/issues
[C]: in function 'assert'
/usr/lib/lua/luci/dispatcher.lua:330: in function 'dispatch'
/usr/lib/lua/luci/dispatcher.lua:144: in function </usr/lib/lua/luci/dispatcher.lua:143>
The corruption is not something that can be easily fixed by a restart or a reset. In order to get rid of it, you will need to flash the latest firmware on your device.
You can do so by using this link which contains all the steps: Recover firmware after failed flash or file system corruption
The flashing of that new firmware will check the disk for errors and remove the problem areas (scandisk).