I’m re-posting this as they seem to block this information on their support website and it’s a pain to have to call (or you can’t call because you are doing an upgrade out of hours etc..).
Sage 2015 (v21) won’t install by default on Microsoft Small Business Server 2011 (SBS2011). It comes up with a message claiming that the new Sage is only compatible with Windows Vista, Windows 7, Windows 8 and Windows Server Operating Systems…. except you are trying to install it on a server operating system.
Sage claim they have made this change because they have experienced poor performance on SBS servers.. I just blame their last 2014 version, it was slow and bad. Company upgrades on Sage 2014 took 20 minutes.. with version 2015 on the same setup it now takes (as it used to) about 30 to 60 seconds to upgrade a company.
The work around is to either…
a 1) run the installer and get the error message and then close it,
a 2) If you didn’t use winrar, go to start, go to run and type in %temp% and click ok.
a 3) Find the Sage folder in the temporary files list and go into it.
b) use WinRAR and right click on the installer to extract it.
Right click on InstallV.exe and select Run as Administrator.
Sage will install as normal without complaining about the operating system being incompatible.
I presume support article 32387 on the Sage support site is supposed to give these instructions but.. 1) it needs your sage client’s login details to get to it and 2) it gave me a blank page when I clicked to view the article.