What happened as part of the change?
On December 1, 2020 the previous FileSender test system https://filesender-test.aco.net/ become the new production service available at https://filesender.aco.net/.
The system previously available at https://filesender.aco.net/ was renamed to https://filesender-old.aco.net/ and remained accessible until all previously uploaded files expired. Once all files had expired on filesender-old.aco.net the system was removed.
What happened to my data uploaded before the change?
All files uploaded to the previous system remained available for download at https://filesender-old.aco.net/ until they expired.
What happenes to "Guest vouchers" I have issued from the old system?
Invitations to upload files issued from the old system no longer work and no new files can be uploaded to the old system. Instead you can issue and share new invitations from the new system.
I have recieved a "Guest voucher" but that only redirects me to this wiki?
We're sorry for your inconvenience. As part of the system change described on this page we need to prevent the creation of new uploads/files/transfers on the old system (otherwise we could never replace it with the new, much improved, one). That means "Guest vouchers" (i.e., invitations to upload files) sent to you from the old system (before Dec 2, 2020) no longer work.
Please contact the person having sent you the upload invitation and ask them to send you another one. Feel free to point them to this page. 
What happened to my data uploaded to the test system?
Files uploaded to https://filesender-test.aco.net/ before the change remained available until they expired: The server and all data are now accessible at https://filesender.aco.net/. All files and all download links from the test system remained valid and continued to work until they expired.
(At some point URL https://filesender-test.aco.net/ will be removed so only the well-known production system URL https://filesender.aco.net/ should ever be used/accessed/stored in bookmarks/etc.)
Was happened to "Guest vouchers" I have issued from the test system?
Those remained fully functional until they expired. Uploading files using these vouchers happened to the new production system.
What about the FileSender Python client?
If you have used this new functionality from the test system you'll have to update its configuration: To do that please re-download the latest version of the FileSender "Python CLI client" and the "Python CLI Client configuration" ("My profile") and replace any previously downloaded versions. Otherwise the client will fail to connect once filesender-test.aco.net no longer points to filesender.aco.net in the DNS.
Any "API Secrets" generated on the test system continue to be valid and usable on the new production system.
I still have other questions not answered here!
Please feel free to contact the ACOnet Team via e-mail at filesender@aco.net.