I’ve been working a project that uses Qt Charts, which is of course a great library. I created a custom widget that incorporates a QChartView. I then decided to create a designer plugin for my new widget. Unfortunately, after I installed in plugins/designer under Qt Creator’s bin directory, it failed to load, stating “The specified procedure could not be found.” Given the fact that Creator can’t or won’t show you what procedure is missing, I had to do a little debugging. I determined that the Qt Charts DLL wasn’t being found.
The solution was to copy the Qt5Charts*.dll files to the Qt Creator bin directory with Qt5Core, etc. Since Qt Creator is compiled with Visual Studio C++ (in my case MSVC 2015 32-bit), make sure you are copying from the correct bin directory in your installed Qt hierarchy.
This was Qt Creator 4.5.0, Based on Qt 5.10.0 (MSVC 2015, 32 bit)