If you want to convert pages, you go the backkoffice-> Admin-> Content Types-> Convert Pages.
If you choose a single page to convert, it doesn't set the type in the "Convert from Page Type" drop down, but you get a clear message that "Could not convert the page:The chosen page type does not match the selected page. The selected page has page type {type}." which is fine (although would be nice if it detected the page type).
If you want to convert the page to the type which happens to be the default in the "Convert to Page Type" dropdown and you just click the "Convert" button then you get:
Could not convert the page:Value cannot be null. Parameter name: toPageType at EPiServer.Core.Internal.DefaultPageTypeConverter.Convert(PageReference pageLink, PageType fromPageType, PageType toPageType, List`1 propertyTypeMap, Boolean recursive, Boolean isTest) at EPiServer.Core.PageTypeConverter.Convert(PageReference pageLink, PageType fromPageType, PageType toPageType, List`1 propertyTypeMap, Boolean recursive, Boolean isTest) at EPiServer.UI.Admin.ConvertPageType.Convert(Object sender, EventArgs e)
This seems to be the edge case as all other variations of not choosing something appear to be handled.
If you want to convert pages, you go the backkoffice-> Admin-> Content Types-> Convert Pages.
If you choose a single page to convert, it doesn't set the type in the "Convert from Page Type" drop down, but you get a clear message that "Could not convert the page:The chosen page type does not match the selected page. The selected page has page type {type}." which is fine (although would be nice if it detected the page type).
If you want to convert the page to the type which happens to be the default in the "Convert to Page Type" dropdown and you just click the "Convert" button then you get:
Could not convert the page:Value cannot be null. Parameter name: toPageType at EPiServer.Core.Internal.DefaultPageTypeConverter.Convert(PageReference pageLink, PageType fromPageType, PageType toPageType, List`1 propertyTypeMap, Boolean recursive, Boolean isTest)
at EPiServer.Core.PageTypeConverter.Convert(PageReference pageLink, PageType fromPageType, PageType toPageType, List`1 propertyTypeMap, Boolean recursive, Boolean isTest)
at EPiServer.UI.Admin.ConvertPageType.Convert(Object sender, EventArgs e)
This seems to be the edge case as all other variations of not choosing something appear to be handled.
EPiServer.CMS 11.5.0