It's possible the older version is trying to install the license because it has the mjr file type registered. Normally the last program run owns the file type.
When I enter the Registration Code, MC creates a temporary mjr file which also fails to work.
This can happen if:
* You haven't run the current copy of MC at least once and given it the chance to register itself on the system, just before you try to apply the license. Whichever copy (so MC20 vs 21 vs 19) of MC that was
last run is the one that "owns" the MJR files, and also the one that will work through the uninstaller and with Shell Integration.
* You have some kind of security software on the system which prevents it from registering its DLLs or taking ownership of the MJR file extension.
In any case, this is easily solved. You have the MJR file (probably a bunch of them). Take whichever is the most recent, and:
0. Make sure you've launched MC21 at least once, and haven't run any older version since then. Also, make sure MC20 (or an older version) isn't simultaneously running while you do this, perhaps in the System Tray in Library Server mode. The easiest thing is to run MC21 and leave it there running while you do the rest.
1. Select the MJR file in Windows Explorer somewhere (like on your desktop) and right-click.
2. Choose
Open With in the menu that comes up and then choose
Choose Program (or Other or whatever, they keep renaming that choice, to let you browse for a program).
3. In the program browser that appears, navigate here:
C:\Program Files\J River\Media Center 214. Choose the
PackageInstaller.exe application in that folder.
5. Check the box to always open with this application in the future.
6. Done. Click Okay and it'll open and register the copy of MC.
If this doesn't work, then you have something blocking PackageInstaller's ability to do its job, probably some kind of Registry "protection" or cleaning tool.
Yeah... I'll probably revert back to MC20 on my HTPC - it was working fine with MC21 server.
MC20 currently works just fine with a MC21 server. In fact, MC19 also works fine as a client. However, this is not guaranteed to remain the case, and you may have sync issues in some cases. There
were, for example, sync-related bugs fixed in recent builds, and you'll only get the benefit of these fixes if you are running a newer copy of MC21 as both the server and the client.
Using out-of-sync major versions of MC together may work, but is an unsupported configuration. So, if you do this and you have trouble, there won't be much we can do to help.
The registration
should work. It would be best to figure out why it isn't in your case.