Page Builder & Site Origin Editor – Unexpected content error

I am testing how to migrate my site to a new domain by migrating to a laptop. All files and database were transferred and both ‘siteurl’ and ‘home’ changed in the database options table. I also edited the posts and meta tables replace old url with new url wherever necessary. Everything seemed to work OK except links to images. I tracked this down to code like src=”/wp-content/…..”. The new WordPress root is ‘wproot’ which is under the default website root, so editing to src=”/wproot/wp-content/…..” works fine. If now I use SQL to change all references in ‘posts’ to the format above it doesn’t correct them all and when using the editor to see what has happened I get a message ‘Unexpected content of invalid data’. ‘Resolve’ doesn’t make a lot of sense and ‘Convert to HTML’ destroys the layout.
Any advice on how to deal with this problem on migrating a site would be appreciated. Thanks, John