Mozilla released the Firefox 53 version of its browser on April 19, 2017. Firefox 53 drops NPAPI support, which may affect your use of the Aspera Connect plugin on Firefox.
Am I affected?
You are affected if you use Firefox 53 and can no longer use Connect as before. Your web application may tell you that Connect is not installed, even though it is, and transfers will no longer work.
If you are affected, the issue most likely has to do with your web application server, which your server administrators will need to upgrade. Send your server admin the following article for more information: Supporting Connect on your server after the Firefox 52 release
In the meantime, you can also use Safari or Internet Explorer, which are browsers that still support NPAPI and ActiveX respectively.
1. Downgrade your Firefox to version 51 or earlier
Old installers for Firefox 51 can be found here: https://ftp.mozilla.org/pub/firefox/releases/51.0.1/
Additionally, you can stop Firefox 51 from automatically upgrading by following the steps below (note: this may be a security risk as you will not receive security updates):
a. Select the 3 line menu button in the upper-right corner, and click Options (or Preferences)
b. Click Advanced, then click the Update tab.
c. Select Never check for updates (not recommended: security risk)