'Apply request failed with status' on everything I do

[RFisMagic]

I have installed OpenWrt 18.06.1 r7258-5eb055306f on a Linksys WRT1900ACS and things seem to work pretty well; I can navigate through all of the screens, I can SSH into it, but...

1. Whenever I change any configuration settings through Luci my changes show up - but when I click 'Apply' I always get the message "Apply request failed with status", and the 'Unsaved changes' counter goes up by the number of changes that I made. Clicking 'Save' doesn't change the 'Unsaved changes' counter. When I power cycle the router the changes are gone.
2. 'Status Overview' has dashes for Local Time, Uptime, Load Average, Free, Total, and Buffered Memory, and Active Connections. 'Active DHCP Leases' shows 'Collecting Data'.
3. 'Realtime Graphs' contains nothing but zeros.
4. 'Firewall Status' contains non-zero packet and byte counts; they look reasonable.
5. I don't see any errors in either the System Log or the Kernel log. Just to make certain I plugged in a USB drive, then tried to apply changes and got the 'Apply request failed with status' message. The USB drive messages are still the last messages in either log.

I searched the forum for this error message but didn't find anything - does anyone have helpful troubleshooting suggestions?

[lleachii]

Try flashing the router again (using sysupgrade this time). Perhaps the partition that saves settings is having an issue.

[RFisMagic]

I flashed the sysupgrade firmware, with 'Keep Settings' unchecked,and get the exact same behavior. However, one change does survive reboot - I changed the default password, and that change survived a power cycle.

[jow]

Sounds like a JavaScript error, try clearing your browser cache.

[RFisMagic]

Ah, exactly right! It was a JavaScript error, but not due to browser cache - NoScript was blocking it. I thought that I had the router address whitelisted, and NoScript didn't show a little '1' to indicate that it was blocking anything.

Thank you jow!