I dunno if it really was worth attempting the upgrade, but as a geneal rule I like to keep software at latest version. Just an old habit.
Anyhow, I am committed now I think, because attempting the upgrade didn't work and rolling back with a restore from backup has caused my "host settings" to fail. I tried the permissions settings on the windows\temp folder, that didn't help. I tried restarting IIS and that didn't help. Rebooting the server didn't help either.
I'd be okay with not upgrading if I can get the host settings working again, but perhaps I'll try the ugrade again and see if that works.
Here is the complete error mesage, if it helps. It's all greek to me.
Error: Host Settings is currently unavailable.
DotNetNuke.Services.Exceptions.ModuleLoadException: C:\Inetpub\wwwroot\dnn\admin\Host\FriendlyUrls.ascx.vb(44): error BC30560: 'RewriterRuleCollection' is ambiguous in the namespace 'DotNetNuke.HttpModules.Config'. ---> System.Exception: C:\Inetpub\wwwroot\dnn\admin\Host\FriendlyUrls.ascx.vb(44): error BC30560: 'RewriterRuleCollection' is ambiguous in the namespace 'DotNetNuke.HttpModules.Config'. ---> System.Web.HttpCompileException: C:\Inetpub\wwwroot\dnn\admin\Host\FriendlyUrls.ascx.vb(44): error BC30560: 'RewriterRuleCollection' is ambiguous in the namespace 'DotNetNuke.HttpModules.Config'. at System.Web.Compilation.BuildManager.PostProcessFoundBuildResult(BuildResult result, Boolean keyFromVPP, VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetBuildResultFromCacheInternal(String cacheKey, Boolean keyFromVPP, VirtualPath virtualPath, Int64 hashCode) at System.Web.Compilation.BuildManager.GetVPathBuildResultFromCacheInternal(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.BaseTemplateParser.GetReferencedType(VirtualPath virtualPath, Boolean allowNoCompile) at System.Web.UI.BaseTemplateParser.GetUserControlType(VirtualPath virtualPath) at System.Web.UI.MainTagNameToTypeMapper.ProcessUserControlRegistration(UserControlRegisterEntry ucRegisterEntry) at System.Web.UI.BaseTemplateParser.ProcessDirective(String directiveName, IDictionary directive) at System.Web.UI.TemplateControlParser.ProcessDirective(String directiveName, IDictionary directive) at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) --- End of inner exception stack trace --- at System.Web.UI.TemplateParser.ProcessException(Exception ex) at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) at System.Web.UI.TemplateParser.ParseInternal() at System.Web.UI.TemplateParser.Parse() at System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() at System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) at System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() at System.Web.Compilation.BuildProvidersCompiler.PerformBuild() at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at DotNetNuke.UI.Skins.Skin.InjectModule(Control objPane, ModuleInfo objModule, PortalSettings PortalSettings) --- End of inner exception stack trace ---