What happened as part of the change?
On December 1, 2020 the previous FileSender test system https://filesender-test.aco.net/ become available at https://filesender.aco.net/, replacing the old system.
The system previously available at https://filesender.aco.net/ was renamed to https://filesender-old.aco.net/ and will remain accessible there for a few days so that all previously uploaded files can continue to be downloaded (until they expire, as usual). There will be no need to manually access filesender-old.aco.net and no new files can be uploaded there. Once all uploaded files have expired on filesender-old.aco.net the system will be removed.
What happened to my data uploaded before the change?
All files uploaded to the old system remain available for download at https://filesender-old.aco.net/. Any "Download Links" you may have shared with others will continue to work fine (until they expire): These will automatically be rewritten to https://filesender-old.aco.net/ and can be downloaded from there. You are no longer able to add or remove any data from the old system. All data on the old system will simply expire and be deleted automatically (as usual).
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?
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 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 remain available: The server and all data are now accessible at https://filesender.aco.net/. All files and all download links from the test system will remain valid and will continue to work until they expire.
(At some point after the change the server the 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 remain fully functional until they expire. Uploading files using these vouchers will happen 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 re-download (or manually update) its configuration file: To do that please re-download the latest version of the FileSender "Python CLI client" and the "Python CLI Client configuration" ("My profile") to update the server name encoded into the client as well as any other changed settings. 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.