Hello me again.
RESOLVED IT
I suspect in my case it was connected with using ALL IN ONE MIGRATION PLUGIN>
Anyway, I have fixed it as follows:
1 create new empty wordpress site
2 BEFORE Upgrading to 4.5.2 migrate the backup to the new site
3 update all plugins and themes etc BUT NOT 4.5.2
4 check it works (mine did)
5 upgrade to 4.5.2.
6 stopped working and got error message immediately.
7 have a cup of tea and relax (I am british)
8 google the issue again
9 found this site https://www.wpbeginner.com/wp-tutorials/how-to-fix-error-too-many-redirects-issue-in-wordpress/
10 part way down page found this
Change Site URL Without Access to Admin Area
In case you don’t have access to WordPress Admin area, you can still update these settings by defining them in wp-config.php file. Simply connect to your website using an FTP client. Once you are connected to your site, you will find wp-config.php file in your site’s root directory. You need to download and edit this file using a text editor like Notepad. Simply add these two lines to the file and don’t forget to replace example.com with your own domain.
1 define(‘WP_HOME’,’https://example.com’);
2 define(‘WP_SITEURL’,’https://example.com’);
Save the file and upload it back to your web server. Now try to access your WordPress site. If you still can not access your site, then try to add your domain with www prefix.
11 did as suggested, using my own local host URL where it says “example “
12 It worked
13 Have another cup of tea and make another backup.
hope that helps
regards
Andy