May I ask if this behaviour continues even when Cloudflare is in “Pause” mode for your domain?
You could determine if this behaviour continues even by using a “Pause” option at Cloudflare as follows:
- Use the “Pause Cloudflare on Site” option from the Overview tab for your domain at dash.cloudflare.com .
- The link is in the lower right corner of that page.
- Give it five minutes to take effect, then make sure site is working as expected with HTTPS.
- Re-try with updating.
- Upon success, un-pause and continue using Cloudflare.
More information about this type of the error can be read at the article from below: