@barbara,
Thanks for giving the tip. That did help.
The issue is in the Reading Progress Bar extension in PHP v8. We’re working on a fix.
Until then, if you’re still on PHP v8, you can disable the Reading Progress Bar extension from the Mighty Addons Dashboard > Extension > Switch off the Reading Progress Bar.
Thanks again for your patience. I’ll let you know here as soon as we pushed the fix.
Thanks.