I've been building a new site locally, for the first time working from the Elemental theme as suggested for newbies/numpties like me.

The amendments I'd made to the standard range of page types, attributes and pages was all going fine until I started to alter the Portfolio Project page type from the Dashboard - I edited the form, and the output to reflect the project topics I'd successfully changed, and the project attributes I'd added.

Once I'd amended the output, these changes now mean that the pages I'd set up no longer display when trying to view or link to them, and new portfolio project pages can't be created successfully.

I've tried undoing all the changes I made by comparing the page type and attribute forms with another 'vanilla' site I practiced with last week, but this has not resolved the problem.

Is there any way to restore the default page types and attributes for the default 'Portfolio Project' to remove the error?

Error is 'strlen() expects parameter 1 to be string, array given' [which doesn't point me at which parameter is the problem.