@amoun what HTML5 validator are you using?

With the in-skin login page:

1. [inc/_core/_template.funcs.php]
   Line 2186: empty action; modified to NULL

Does the error disappear after applying the change above? I mean, the empty form action remains in the code declaring form_action empty and also as NULL.

When logged in

1. [inc/users/model/_user.func.php] Lines (193,199,235,236,213,217,219,236,704,768)
   Did all lines mentioned but (235 and 236) removed errors

Can you describe what error are you fixing here?

1. Sorry for omitting explanation in the second. They relate to the use of the '&' symbol rather than '&'

   E007 Found '&' within 'href'. You should use '&amp' instead:

   There are many cases of them in many files but (235 and 236) removed the obvious ones

2. To remove validation error of empty action
   In the case of inserting the NULL as the action value, yes it solves the validation problem.
   line 2186 was

   'form_action' => '',

   now:

   'form_action' => NULL,

@amoun all right. Please, tell us what validator are you using.

Thanks.

Yes I should have said, I get in such a hurry after getting bogged down with validation
https://validator.w3.org/nu/

and later I'll get around to some css stuff :)
http://jigsaw.w3.org/css-validator/

I have links in the footer on my site, http://calstock.org.uk/elf.php, that dose the page viewed, not that I've done every page, but every time I upgrade I do the home page and the login page.