I have SP 2019 farm, the document library migrated from MOSS 2007 is showing classic page even "New Experience" enabled in List Settings
After some research, I found some other web part other than XSLTListView is added to that page view. after removed those webparts page working like a charm.
I have followed below steps to find out the issue:
- To get page rendering type (REST type) copy and page below rest end point in browser (update server host name): http(s)://server/_api/web/getfilebyserverrelativeurl('/sites/dev/ECMTest/Forms/AllItems.aspx')/pageRenderType
- check the response value: I got value 1, then checked with the previous Reference URL i got description about the problem (MultiWebpart)
I also had another Webpart in my View Page, so had to Delete that Webpart and then it worked for me (Make sure you clear Cache after Deleting webpart or try in another browser)
I followed these Steps:
Checked the Page Rendering Type of 2 Diff Libraries View Page
The Library which has Custom Webpart added, Returned 1 https://tenanturl/_api/web/getfilebyserverrelativeurl('/WTABTARegistratieDatabase/Document/Forms/ModernView.aspx')/pageRenderType
Another Library which has no Webpart, returned 100(Modern) https://tenanturl/_api/web/getfilebyserverrelativeurl('/sites/WTABTARegistratieDatabase/SiteAssets/Forms/AllItems.aspx')/pageRenderType
Deleted custom webpart, and now it worked.