Hello,
Thanks for contacting us, and sorry for any inconvenience that might have been caused due to that.
It seems the memory on your server is getting exhausted because of the functionality of Rank Math. Please ask your hosting provider to increase the memory to at least 512MB or 1GB for big websites to see if that resolves the issue for you.
Let us know how it goes. Looking forward to helping you.
Thank you.
Hi,
I’ve checked this, but the issue stays. I can save all pages and shop pages. The issue is only when I save the header template in breakdance. When I have activated the plugin rank math the only problem then is that I can’t save the header template.
Hello,
We might need to take a closer look at the settings. Please edit the first post on this ticket and include your WordPress & FTP logins in the designated Sensitive Data section.
Please do take a complete backup of your website before sharing the information with us.

It is completely secure and only our support staff has access to that section. If you want, you can use the below plugin to generate a temporary login URL to your website and share that with us instead:
https://wordpress.org/plugins/temporary-login-without-password/
You can use the above plugin in conjunction with the WP Security Audit Log to monitor what changes our staff might make on your website (if any):
https://wordpress.org/plugins/wp-security-audit-log/
We really look forward to helping you.