This happens when you try to add a favorite from the context menu and either QAP is not running or QAPmessenger (the program called by the context menu) cannot find QAP.
First, make sure QAP is running.
If it is, there may be an issue with your context menus. Because you use the portable, you need to do this manually. Try uninstall your context menus and reinstall them (see "Setting up Context menus manually (for portable installation users)" in
https://www.quickaccesspopup.com/?s=qapm...ble#manual