I am using Sonar Platinium 2016.10 in Windows 10 Pro (all updates installed) and have detected a problem with plugin scan. When I scan plugins I get a failure for XLN Addictive Drums 2 (VST 64) and same type of error for iZotope Alloy 2 VST 64.
The Cakewalk VST scan error says those two plugins caused an error during load.  I tried to uninstall Addictive Drums 2 and reinstall.  I have also reinstalled iZotope Alloy 2.  Still no improvement. Also tried to roll back to Sonar from January/Februray
2015 but still the same problem.
 
It also seems like I'm getting problem with other iZotope plugins. Cakewalk plugin scan takes ages and seems to get stuck on iZotope plugins.  Sometimes I get a licence verification error message (seems to be a timeout).  When I stop and start the Pace ilok service the plugin scan continues. Seems like there could be a problem with ilok.  I tried legacy version and latest version of ilok software but still same problem. The strange thing is that XLN Addictive Drums 2 is not using ilok and should not be affected by a ilok problem. 

I'm quite stuck here and would like some advice on how to proceed.  Uninstalling/reinstalling every piece of software is a possibility but is very time consuming so I hope there are a few trick I can try before I do full reinstall.
 

Hi. You might have to re authorize some plugins after the Win 10 anniversary update. I had to do this with at least AD2.
All the best.

see the XLN FAQ about your AD2 issue https://www.xlnaudio.com/support/topics/my-product-is-suddenly-not-authorized-wrong-computer-id-or-this-instrument-is-in-trial-mode. Windows updates can trigger this problem.
 

The XLN AD2 stand alone application is working without any issues.  Anyway I tried to remove the XLN and re authorized the computer but still the same problem remains.  Also Addictive Drums (AD v1) and Addictive Keys plugins has never given any errors.

Sometimes the scanner will throw errors when a previously processed plug-in trashes memory. These errors have an option to enable the plug-in. Although the dialog indicates it is risky, chances are the plug-in is OK to enable. If this is not an error with an enable option, it would help to know more about the error.

Another thing to try when resolving scanner problems is generate scan logs. A scan log is created by holding the SHIFT key while clicking the Scan button in Preferences > File > VST Settings. You can use the log to move chunks of dlls in and out of the scan path to narrow down the bad actor(s).

I got the choice to disable or enable plug-in.
 

I occasionally get errors like problems finding MAIN CALL with plug-ins that have always worked. I enable the plug-ins and never have issues with them. You may be able to figure out exactly which plug-ins are causing the problem but I have never bothered with the exercise.

I think I got it working now.   I set the plugin scanner to:
-rescan failed plug-ins
-not re-scan existing plug-ins
 
First scan gave MAIN CALL errors on AD2 and iZotope Alloy 2. I choose to disable those plugins.
Then when the scanning halts after scanning many iZotope plug-ins I restart the Pace Licence service every time the scanning seem to stop. Then the scan continues. After it finished I perform a new scan again and again until all plug-ins seems to be found.  I have tested the AD2 VSTi now and it is loading in Sonar  :)