i have the same problem here.
SS 3.1.2 NEW fresh install
maxskitter is the only extra module installed
Tried userforms master and 1.0... both the same problem
Userforms installs well
In dev mode finally got some errors:
ViewableData->renderWith(SSViewer)
LeftAndMain.php:588
{closure}()
call_user_func(Closure)
PjaxResponseNegotiator.php:82
PjaxResponseNegotiator->respond(SS_HTTPRequest)
LeftAndMain.php:565
LeftAndMain->show(SS_HTTPRequest)
RequestHandler.php:288
RequestHandler->handleAction(SS_HTTPRequest,show)
Controller.php:194
Controller->handleAction(SS_HTTPRequest,show)
RequestHandler.php:200
RequestHandler->handleRequest(SS_HTTPRequest,DataModel)
Controller.php:153
Controller->handleRequest(SS_HTTPRequest,DataModel)
LeftAndMain.php:441
LeftAndMain->handleRequest(SS_HTTPRequest,DataModel)
AdminRootController.php:93
AdminRootController->handleRequest(SS_HTTPRequest,DataModel)
Director.php:360
Director::handleRequest(SS_HTTPRequest,Session,DataModel)
Director.php:152
Director::direct(/admin/pages/edit/show/13,DataModel)
main.php:189
i can create the page... tricky view (it doesnt open but when pressing reload it shows with errors above) it but cannot create the form itself... its a blank page. All other tabs seems to work!
further it breaks tinyMCE colorpopup. It opens now like a totally new page by selecting the color and when selected it goes back to the normal state.