[Steven Zahm]

@ paul

Hmmm, this error does not make sense. The template index is wat is being added/set. I am unable to replicate this error? Which template are you customizing?

Can you please create a temp admin using this plugin so I can take a closer look?

https://wordpress.org/plugins/temporary-login-without-password/

Reply back, as a private reply, with the login link.