Problem: Application Icon on Windows Taskbar Becomes White Square

I was using a Windows 10 system. I noticed somehow the icon of application on the taskbar became a white square, like this picture shows,

I figured out a solution to resolve this. That is to delete the thumbnail icon cache that we can find at %LOCALAPPDATA%\Microsoft\Windows\Explorer, i.e.,

1. Open a Windows Command Prompt window
2. Do the following from the command line on the Windows Command Prompt window
1. taskkill /F /IM explorer.exe
2. del %LOCALAPPDATA%\Microsoft\Windows\Explorer\thumbcache_*.db
3. explorer.exe

Sometimes, it is also necessary to remove all the thumbnails themselves, i.e., run the Disk Cleanup application. From the command line, that is,

1. Run the Disk Cleanup application, i.e., cleanmgr.exe
2. Uncheck everything using the user interface, and check "Thumbnails" (See the screen shot). 
3. Click OK to confirm
4. Exit the Disk Cleanup application

The system will rebuild the thumbnail cache and the thumbnails.