DNN Blog does not allow to save new posts or comments

[Yagun]

We upgraded DNN from 6 to 9.1.1. The Blog module was upgraded to 6.00.5, then to 6.3.0, then to 6.04.01. Now the blog shows the posts and comments, but does not allow to create new posts or comments.

Error message:

ModuleId:454 ModuleDefId:123 FriendlyName: ModuleControlSource:DesktopModules/Blog/PostEdit.ascx AbsoluteURL:/Default.aspx DefaultDataProvider:DotNetNuke.Data.SqlDataProvider, DotNetNuke ExceptionGUID:db57f36e-cd6f-4541-a389-dc26f122f9e6 AssemblyVersion:9.1.1 PortalId:0 UserId:24 TabId:88 RawUrl:/El-Blog/ctl/PostEdit/mid/454/Post/323 Referrer:************El-Blog/ctl/PostEdit/mid/454/Post/323 UserAgent:Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0 ExceptionHash:EpWiJC2IEM7+2eVutsX4Ugr8ANo= Message:Object reference not set to an instance of an object. StackTrace: InnerMessage:Object reference not set to an instance of an object. InnerStackTrace: at DotNetNuke.Modules.Blog.Integration.NotificationController.PostPendingApproval(BlogInfo objBlog, PostInfo objPost, Int32 portalId, String summary, String title) at DotNetNuke.Modules.Blog.PostEdit.cmdSave_Click(Object sender, EventArgs e)

[valadas]

@Yagun what version of the Blog module was used in Dnn 6 before you started upgrades?