Diving deeper, I notice the error was second after the one below. I gather the first triggered the second.
DotNetNuke.Services.Exceptions.ModuleLoadException: Error: Contact Form is currently unavailable. --->
System.Web.HttpCompileException: D:\HTTP\dnn2\v6-5.6.3\DesktopModules\Dynamic Forms\DynamicForms.ascx(57): error BC30451: 'GetProgressURL' is not declared. It may be inaccessible due to its protection level.
at System.Web.Compilation.AssemblyBuilder.Compile() 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, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
at System.Web.Compilation.BuildManager.GetVPathBuildResult(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean ensureIsUpToDate)
at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at DotNetNuke.UI.ControlUtilities.LoadControl[T](TemplateControl containerControl, String ControlSrc)
at DotNetNuke.UI.Modules.ModuleHost.LoadModuleControl()
--- End of inner exception stack trace ---
at DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(String FriendlyMessage, Control ctrl, Exception exc, Boolean DisplayErrorMessage)
at DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(Control ctrl, Exception exc, Boolean DisplayErrorMessage)
at DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(Control ctrl, Exception exc) at DotNetNuke.UI.Modules.ModuleHost.LoadModuleControl()
at DotNetNuke.UI.Modules.ModuleHost.CreateChildControls() at System.Web.UI.Control.EnsureChildControls() at DotNetNuke.UI.Containers.Container.get_ModuleControl()
at DotNetNuke.UI.Containers.Container.ProcessModule() at DotNetNuke.UI.Skins.Pane.InjectModule(ModuleInfo objModule)