Theme disappears after saving and trying to edit it again

Your software
My Mautic version is: 4.4.6
My PHP version is: 7.4.36
My Database type and version is:

Your problem
My problem is:
I modified the sunday theme a little bit.

It appears in the email builder. I can select it and edit it. Then I’m closing the editor via “save and close”.
When I want to make changes i.e. I’m launching the builder again, the theme is not there but an empty page.

Did s.o. here made similar experience?

Many thanks

These errors are showing in the log:

Steps I have tried to fix the problem:

Hi, did you use emojies?

Hi Joey,

No, no emojies. I just changed some images i.e. Logo and Header Image, and added 2 more social media buttons.

Are you using the grapesjs?


“name”: “Sunday”,
“author”: “Mautic team based on a theme by Sendwithus”,
“authorUrl”: “”,
“builder”: [“grapesjsbuilder”],
“features”: [

Could you plz check in the DB in the emails table if you have declaration as first string in the custom_html field?
If not, add it and check the email.

This is what I have under custom_html

!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Trans…

It must be a problem of the template itself.
The sunday template has the same problem. So, it is not because of my changes.

Maybe I should just take another template and modify that.

Or is it be because there is no builder: [“legacy”] in the config file?

YESSSS, the [legacy entry was missing.

When do I need the legacy and when not? I thought the legacy builder is deprecated?

NO! I’m experiencing the same problem (blank editor) again.

I think that the problem is, that while changing the template, I deleted some parts of the table, thus not showing up any more.

I’ll get through this! Many thanks for helping.

Well, the problem is in the sunday template.

I took another template as a basis for my changes and voilá it works.