Hello,
Previous releases can be downloaded from our web archive located at
http://down1.opensightsoftware.com/archives/
I understand that it is critical that you get FlashFXP back up and working but I do have a few questions that will help us resolve the problem.
What version of Windows OS are you using?
What version of FlashFXP did you upgrade to?
Please verify that the version of FlashFXP installed is in fact the latest, do a manual update check (Main menu > Help > Check for new version) or compare against the version listed on the website
https://oss.azurewebsites.net/download
What version of FlashFXP did you upgrade from?
Are you using a software firewall, if so which one?
Some firewalls require re-authorization to allow FlashFXP to work after an update.
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Update:
Also since Active mode is working you might consider changing the "Data connection mode" in the site manager from "Passive mode" to "Active mode"
One thought is that perhaps the firewall or the firewall configuration changed on the machine running the FTP server and it is now blocking passive mode FTP connections.