I was rather disturbed to learn that Poser 9 (and Poser Pro 2012?) won't run under Windows 8.1.  This seems like a big issue for Poser users, as important as any bug in Poser itself, and I kind of wonder if there should be a stickied thread about the problem (and any related compatibility issues that develop), to serve as a ready reference as users upgrade.  It would be useful if we could gather what we know about these issues in one place, this thread or another, and have that thread where we can easily find it.

What do we know about compatibility of old Poser versions with new or updated operating systems?  Some versions of Poser may not work with new versions of Windows, but which ones?  Has anyone tested this?  Some Poser Python elements, too, don't work on certain versions of Mac, which may be worth noting.  Does anyone have any information? 

To my understanding, Windows 8.1 introduces a fatal conflict with a Flash-related dll.

Flash is used in Poser 8 / Poser Pro 2010 and up, for handling the Library in internal mode.

The issue can be resolved in various ways:

 - for Poser 10 / Pro 2014 SM released a SR to repair the issue
 - for Pro 2010 / 2012 the ini file can be altered manually to force the Library into external mode, and to use Adobe Air instead (requires Air to be installed)
 - for Poser 8 and 9 there is no solution, although I think there was a thread referring to the specific dll, and to the way replacing it with a conflict-free version

Next to this, Poser 8 and earlier face issues on Win 7 and up (or even Vista) related to Runtimes / content being installed in the Program Files environment, due to the protection scheme that prevents (user) data to be mixed with program files, known as UAC (User Acces Control).
Some resolve this by running Win-XP, others disable UAC, Poser 9 and up have improved external Library handling.
Unfortunately, older product installers require Runtime subfolders in a folder that has a poser.exe file in it - even if it's a 0 bytes file. And so on.

Anyway, Poser not only has system requirements, it also has some user requirements as well. Handling "progress" seems to be one of them :-)

So earlier versions of Poser, prior to 8, have no troubles?  That's good news.  Also good news that there are potential solutions to some of the problems.  :woot:  I'd be interested in the thread which explains how to replace the dll for Posers 8 and 9.

This is the thread containing a solution:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2873889

the thread is: http://www.renderosity.com/mod/forumpro/showthread.php?message_id=4107310&ebot_calc_page#message_4107310

but now I re-read it, I'm not sure it's really about the Win 8.1 problem. On the other hand, I have not seen issues reported on P7 and earlier when upgrading to Win8.1
Other people might be better informed, hope they step in.

To my understanding P7 and earlier did not use Flash for the Library, it was introduced by BagginsBill (Ted Czotter) who completely rewrote the Library for P8, introducing Air for the External Library in Pro2010 as well.

Quote - the thread is: http://www.renderosity.com/mod/forumpro/showthread.php?message_id=4107310&ebot_calc_page#message_4107310

but now I re-read it, I'm not sure it's really about the Win 8.1 problem.

Correct; this was an issue with a Flash update...