Hello,
To understand the root cause for the failure, in a root shell on the server, run:
# . /etc/profile.d/kaltura*base.sh
# kaltlog
Then make the request and look at the errors being outputted. Once you have these, open the relevant log file [most probably /opt/kaltura/log/kaltura_api_v3.log], locate the final error and trace back to the beginning of the flow. Paste the stack trace here.
In parallel, open the dev tools in your browser and look for errors in the “console” and “network” tabs. Paste your findings and we’ll take it from there.