I downloade Foxit Reader from here and then extracted and installed it.
However, after using it for a while, Foxit Reader freezes with a popup:
Foxit Reader is not responding, please wait or force quit
I don't know why this happens. Do you know any solution for this issue?
Start Foxit without opening any pdf file. Go to Edit --> Preferences. Go to Updater and uncheck. Go also to General and Disable ConnectedPDF features. I haven't tested if only one step would be sufficient.
Yes, this always happens to me with Foxit Reader. My workaround is to Force Quit it until it starts responding. Usually it takes at least 2 to 3 tries.
You can see what's happening on your system with a command like:
grep -i -B 10 -A 10 'foxit' /var/log/syslog
But I love the app and it's worth it to me to go through this inconvenience until this gets fixed. I just filed a support request with https://www.foxitsoftware.com/ and included some of the log output. It may help if you also report the specifics of your problem to them.
I solved it running the installer as administrator. I hope that could be useful for you.
FoxIt seems to be no longer maintained. You can check out the official statement in the foxit forum.
TL;DR; The existing version of FoxIt Reader requires Ubuntu Desktop 14.04 - 16.10. So it doesn't support Ubuntu 20.04 (and also not 18.04, and so on).
