Used the Project - Other - Back Up Project to a zip file.

Have downloaded v1.57 R9 and update files.

Before I execute these files, is there any else I need do.

Obviously don't want to lose any web pages!

Thanks 

Thank you for the advice.  Now have both versions of the software running ok.

Unfortunately uploading is causing issues with corrupted pages and missing pictures.

IONOS (the host) says "It shows that the website is created through html which involves scripting."

Same result on uploading home page.

No image

Pop up menu has expanded

You MUST 'insert the images into the project'.

Though it is possile to simply copy these images from source to any place of the site,
that is wrong, that does not work, because it is a CMS system.
Which requires the images to make them 'known to the project'.

How to do that?

Each image element has three small buttons beneath.
The first (leftmost) button invokes the resorce handler. Through that handler ALL images have to be installed/activated - to be made known to the project.

A file list pops up, containig the images; those images may be added (made known) to the particular image element of OE.

You will be asked to select your (to be added) image from this list.
If the image is not contained in that list, it can be added from original source.
And then it can be selected for the image element.

The second button beneath the image element may be used for an another image, p.e. different in size, dimmed, link, ....

The third button (right) would lock the image, not needed now.

That should do the job.

There is a possibility to 'optimize' these known images. You will find it under Preferences...Maintenance...Optimize.
Before performig this optimization, it is recommended to create a backup.

Size of my project: some 500 pages, with about 12.000 images.
OE is still not at the limit.
https://blumendigi.com/

Simply upload that zipped file to your Domain. Filezilla.
Insert a complete link to that file into your OE project.
Image link, text link, ...