Every time I try to load a VST 3 synth, Sonar crashes. Anyone else have this issue or figured out what the problem is?

There are some issues with using a few of the VST3 synths from the Arturia V Collection, and if these are the ones giving you trouble, the current work-around is to get rid of the VST3 versions and use the VST2 versions - they sound identical, so you are not losing any sound quality in doing this.
 
I am not sure where the issue lies, but there are several folks in the Sonar forum community using the above, until some sort of fix arrives.
 
If you are having trouble from some other VST3, please list which one or ones are failing.
 
Thanks, 
 
Bob Bone
 

Based on some of the work Bitflipper did with his VST inventory tool, it seems that some (all?) VST3 files are actually wrappers adding VST3 functionality to the underlying VST2 DLL. If true, it is obvious that some developers were more lax in creating these (all of my VST3 files work fine, and the VST2 versions appear identical). Bob's post above is definitely recommended.

Clarification of specific synths would be helpful to a solution, since the title can be misleading.

All of my VST3 synths are from Arturia. Go figure. I will keep using the VST2 versions.

Well that's good news that it appears thus far that only some of these Arturia VST3 plugins are struggling, and one of the nice things about these forums is that there is a good chance that at least one other forum member has encountered a given issue before.
 
Those Arturia synths to me sound fabulous, and I am VERY happy I was able to pick them up on a 50% off deal they were running about a year ago.
 
Bob Bone