Hello again,
Yes I’m posting another annoying question!
Is there a way to upgrade to a newer version MATE without upgrading to a newer version of Ubuntu?
My Raspberry Pi is running: Ubuntu MATE 16.04 with MATE version 1.16.2
My Desktop PC is running: Ubuntu MATE 18.04 with MATE version 1.20.1
Is it possible to get them both running the same current version of MATE without upgrading the RPi to 18.04?
Or are the mutually exclusive?
Hello Kernel_Panic. It would be nice if you would categorize your next annoying question under the Support & Help category just to keep this site a bit more organized and to help those who might answer your requests.
Thanks…
Oops!
Sorry!
My fault!
I’ll write myself a note. Thanks for the friendly reminder! 
To answer your question, NO it’s not worth even trying until a formal 18.04 release on the Raspberry Pi is released.
In theory you should be able to do this, because undoubtedly much of the MATE 1.20.1 desktop was originally developed using the 16.04 kernel and libraries, but I wouldn’t count on it still installing cleanly, especially on an ARM CPU based setup like the Raspberry Pi, because Linux developers delight in setting often totally unnecessary “latest and greatest” dependencies, so if you try to do this, I suspect that you will run into dozens, if not hundreds, of “can not meet required dependencies” type installation errors.
I am not sure what the snag is getting MATE 18.04 running on the Raspberry Pi, but if it was easy to resolve, then we wouldn’t still be waiting on the official release.
I kind of figured this was not possible, but it never hurts to ask!
When you look at these systems side by side, they look identical, but then you go poking around and see all kinds of little differences. Oh well, I guess I’ll just have to wait for an official release. Thanks for you help!
In theory, it could work if someone packaged the latest MATE against 16.04 but it would depend on many new dependencies and if those dependencies (packages) are installable in 16.04. MATE underwent a major milestone between 16.04 and 18.04 (around MATE 1.16?)
16.04 and MATE were built with a library known as GTK2, but newer versions of MATE went GTK3 only, so 18.04 is packaged up as a “GTK3 experience out of the box”. If you’d upgraded MATE, you’d end up with both GTK2 and GTK3 libraries used by programs which isn’t efficient on memory resources.
I was having an issue that I thought could be rectified if both my machines were running the same version of MATE but not necessarily the same version of the OS. I was just overthinking the solution and I just need to find a work around. I won’t get into it, but I just wanted to know in case we could use that as a stopgap between waiting for 18.04 to become available for the Raspberry Pi.
At any rate, thanks for you help!