Unable to restore backup (HTML detected)

Hi,

I’m unable to restore an UpdraftPlus backup. It seems to go wrong somewhere in the plugin section of the restoration.

The message I get is: “UpdraftPlus Restore error: HTML was detected in the response. You may have a security module on your webserver blocking the restoration operation.”

If it matters, I’ve been able to restore UpdraftPlus backups on this website before (a month or two ago) without any issues.

Here is the log file:

https://www.mariaterbeek.nl/wp-admin/options-general.php?action=downloadlog&page=updraftplus&updraftplus_backup_nonce=c9000e36fab1

What can be done?

Thank you in advance.