Hello Alex, The components of MX01/9.6.02 (and newer) are not compatible with older versions. When you check the readme of the Service Pack MX03 (mx03w32.txt) then you can find the following note:  

(2). Recompilation requirements
-------------------------------

For Uniface 9.6 patches are fully incremental. This means that any newer 
patch can be installed on top of an earlier patch or minor version. 
For example: It is possible to install patch X301 on top of 9.6.01/patch 
X101. Doing so, the installation will automatically be upgraded to 
Uniface 9.6.03 with patch X301.

Although we try to prevent a recompilation requirement for a patch or 
service pack, a recompilation of the components is sometimes required after 
installation.

After installation of MX01/9.6.02 and later patches/service packs, a 
recompilation of all components needs to be done if these patches are 
installed on top of a Uniface version or patch older than MX01/9.6.02.

  Hope this helps. Kind regards, Daniel

"9.5.x, 1 project (Z) in 9.6.01"  Mixing components compiled between point versions, for example 9.5 and 9.6 is always a no-no. I'd say in the case of 9.6, the risk of crashes, corruption, etc is significant because of all of the GUI enhancements that were delivered and there was a huge amount of code re-factoring as a result of the 64 bit windows project.