Server move – redirect issue

Hi All

Forgive me if this has been discussed before, I couldn’t seem to find anything to answer my query…

I have developed a multisite website on for all intensive purposes https://www.developmentsite.co.uk/clientname/ and I am trying to move the entire site to https://www.clientsdomain.co.uk (new domain and new directory)

I backed up the entire site and db and changed the config file and did a search and replace on all references to the domain in the db replacing them as required however when I visit the site I have a strange problem…

The site looks fine and all the sub-sites are working great however the default site has some form of redirect issue, basically when I click on any of the links to say /about/ it just re-directs me back to the homepage

also if I try and go to /wp-admin I get an error message saying could not modify headers message

does anyone have any ideas please?

thanks
John