I already have the solution "SPListFilter 2.3 Server" installed in our company SharePoint Server 2013. and it works well. I've got this solution from this link http://splistfilter.vitalyzhukov.com/download/. and today I have installed the newer version of the solution "SPListFilter 3.03". but the problem I am facing is that when I tried to add the "SPListFilter 3.03" web part in my page, I had this error: –
A Web Part or Web Form Control on this page can not be displayed or
imported. The type could not be found or it is not registered as safe.
Can someone therefore give his opinion on this error?