Hello Graeme,
I am sorry for the issue.
What PHP version are you using for the hosting space, and is the PHP parameter display_errors active? If so, please disable it.
Did you add any new blog posts, and if so do they have any special characters in their titles or the name of the categories, or is the only thing that changed the software version?
Thank you.

Eric

What PHP version are you using for the hosting space, and is the PHP parameter display_errors active? If so, please disable it.    NO IDEA - WHERE DO I FIND THIS

No special characters added to my knowledge. Nor titles. Just since software update. Usually I do not update software for months after each release as always causes headaches but I accidentally click this one the other day. 

Hello Graeme,
could you provide me with a copy of the project so that I can take a closer look?
You can export it in Step 5 - Export, choosing the Export the project option to generate an IWZIP file.
You can then upload the file with https://www.swisstransfer.com/ or similar services, and provide a download link at sales @ incomedia.eu (without the spaces)
Thank you.

Regarding the PHP version and the display_error, they should be options available on the control panel of your hosting space, or you can ask the support of your provider about it.

Eric

Did you get this? I sent it in yesterday.

Hello Graeme,
yes, I received the e-mail and will take a look at the project as soon as possible.

Eric

Hello Graeme,
the error is not due to the update, but rather to the last blog post that was added, in which a part of the text is triggering an error.
I was initially able to replicate the error on a different hosting space, and after deleting the title of the latest post and writing it again, the blog resumed working.

Eric