This exact wording only appears in the admin's own Preview for the page (not to site visitors): it means the page's saved Template points at a template file Sprwt's server can no longer find ("Page invalid Template"), or one that exists but is missing its required file header — typically a very old custom template ("Old Format Template"). To fix it, open the page, click Settings > Template, and Change to DIY or another template from the list, then rebuild the content with modules. On the live public site the underlying problem shows up differently: a missing template file results in a normal 404 page for visitors, while an "old format" template quietly falls back to rendering the page's raw saved content instead of erroring. If the template was a client-custom one, contact Sprwt support to restore it.