Drizzit
I've been unable to get a single sidechain compression send to work. Causes an immediate crash as soon as I click play. Doesn't seem to matter what compressor I try.

I've had this problem now for a while too. I have a workaround that allows the side chain to work, but it's a pain. Do everything your doing, but instead of hitting play, hit save. Then play, which will crash Sonar. Re open Sonar and your project, and your away. But I still get the odd audio glitch, or audio engine dropout, after re-opening the project, but it doesn't crash Sonar, and rights itself again quickly. 
 
My system is my DAW only, fast and well maintained, so I don't think it's to do with system performance. I wish I could find a fix.....
 
 

This is happening to me as well. Sonar Professional. Very low CPU load with ZERO plugins running, other than the sidechain attempt, and it crashes immediately when I hit play. ASIO driver set at a sample-friendly mixing point.
 
Anyone have any ideas why it's happening? Pretty fundamental DAW move. Thanks for any suggestions as where to start looking for the culprit. 

Thought I would bump this issue. Last side chain attempt immediately crashed on “play.” Hardly any CPU load. No plugs except for the side chain attempt. Working off an SSD with 32 gigs of RAM. I don’t get it.

Lots of smarts on this forum. Hello? Bueller...? Bueller...? :-)

i use the Sonitus compressor for all my side-chaining in CbB (and before that, Sonar Platinum) & have not had any problems with it, in fact i was doing it again last night and the night before etc.  though i have experienced the weird glitches that come with huge projects.  so weird that a sidechain would cause a crash with 32 gigs of RAM.  are there any 32 bit plugins involved with the project?

No. Not mine, anyway. All 64 bit

My theory here is that within a given project, you have 10 various plugins going, some ProChannel stuff, and some soft keys.  Everything is peachy, then you decide to stick in a compressor to duck a track, and boom.  Another mix of stuff and no boom with same compressor. 
 
I've had good luck with these Aux-track methods:

• Ducking bass with kick:  Adjust compressor on bass and route bass tracks to bass buss (I always clone the bass track, kill all the lows, and saturate heavy, and blend in with regular bass to keep bass licks from being buried).  On bass buss, use sidechain capable compressor (i.e., ProChannel PC4K Bus Compressor), and turn on side-chain.  If kick track has no audio, open AD2 mixer and route to both master and output, and then route output of kick track to adjacent “duck” AUX track, and output the Duck-Aux track to trigger the compressor.  Fast attack,  release ~80ms, ~3:1 ratio to get 4-6db GR on bass when kick hits

If, say, ducking vocals with guitar:  On gtr track, route gtr-track-send to new-Aux track, route output of Aux track to trigger on compressor.  
 
 
 

It works fine for me in a project where I'm using the lead vocal to sidechain two compressors, one on a softsynth harpsichord and the other on the Guitars bus. The project has about 20 tracks and numerous plug-in effects and Vi's.
 
One thing I notice is that most of the people getting the crashes seem to still be running SONAR (according to their sigs).
 
I'm running the latest version of Cakewalk by BandLab and it's always just worked for me, so anyone having trouble with sidechaining or any other instability who's still running SONAR might try installing Cakewalk and see if it handles it better.