Hello, Vicul, you wrote: AG>> Remove its call from the code (or replace on InitializeCriticalsection) and all will be OK! V> if all so was simple. OpenCV you speak... we very much on OpenCV, truth all did under Win-7. We applied OpenCV v 2.4 (it and is accessible to this day on https://sourceforge.net/projects/opencvlibrary). I will in passing note that no problems in this plan - neither with MFC, nor with Qt5 at us EXISTING (truth, all under Win-7). V> in the fighting project the solution totals more than 30 projects. And this got out on dll-kah with opencv which I collected You collected OpenCV v 3.3? If to take earlier version OpenCV, compatible with Win-XP (the same OpenCV v 2.4)? This variant is real? At least, for support Win-XP... V> on the same 2013 with v120-xp. That is, the assembly with calls InitializeCriticalsectionEx transited under v120-xp? Strange. Perhaps, this material appears is actual: https://github.com/opencv/opencv/issues/9817 V> And in a solution opencv for one hundred projects. And all 42 dll go with call InitializeCriticalsectionEx. That is - a variant of passage but older library OpenCV - it is actual. I do not know, truth, whether it is possible on in your case. V> on a test program, there it where that inside. I in a wizard created dialog box with two buttons - ok and cancel. V> Well that it only showed this window. Therefore on any it should be launched on . Sorry, not the last two lines - what for "dialog box with two buttons - ok and cancel"??? An essence of this action??? Replaced call InitializeCriticalsection with something another? Or I here not so understood something? Having source codes, I would try to cause all InitializeCriticalsection, instead of InitializeCriticalsectionEx. Certainly, some changes in the existing codes for this purpose be required... Or earlier library OpenCV v 2.4.