Spring Boot + Primefaces - "Unrecognized Content Type" Exception

I had a similar problem migrating existing primefaces 6.2 webapp to wildfly 14. My fix is to add process="@this" to all p:menuitem

Exactly what Tom Bombadil say! If you had @this at the prossess property it will work! In my case, since I load menus from the database using the DefaultMenuModel, I have this:

DefaultMenuItem mi = new DefaultMenuItem();
mi.setValue(m.getDescription());
mi.setProcess("@this"); //IMPORTANT SINCE WILDFLY 14 - Unrecognized Content Type?!
mi.setIcon("id-icon-param");
if (m.isExecutecommand()) {
  mi.setCommand(m.getCommandinstruction());
} else if (m.isLoadasdialog()) {
  mi.setUrl(m.getViewId());
} 
mi.setUpdate("@form");
submenu.addElement(mi);

Hope it helps!

Inovarium

I have the same setup and the same problem. It was caused by f:view tag in my main template.

<f:view contentType="text/html">

Removing it fixed the problem.