Online Store editor session can't be published

Technical Q&A

Topic summary

Issue: Saving theme changes fails with “Online Store editor session can’t be published” after converting multiple sections to dynamic (with schema) and adding many blocks.

Observations: Writing text to a fourth textarea consistently triggers the error; removing blocks or text allows saving, suggesting a size/complexity limit in theme settings.

Resolution: Reduce the size of the theme’s settings JSON. Move large content (e.g., SVG) from customization fields into the code, and prune configuration fields.

Confirmation: Trimming settings_data.json fixed the issue for another user. Deleting “Presets” objects in the Debut theme reduced the file from ~22 KB to ~17 KB, restoring the theme customizer.

Nuance: The exact limit is unclear. Theme 2.0 (Shopify’s newer architecture with distributed settings) seems less affected; a JSON page template >100 KB saves without issues in a different store.

Key terms: settings_data.json = the theme’s settings file; Theme 2.0 = newer Shopify theme framework with modular, distributed settings.

Status: Resolved by reducing settings JSON size; further clarification on limits and theme-specific behavior remains open.

Summarized with AI on February 3. AI used: gpt-5.
1

Hi there, so i am working for a client and they wanted to have the option to change text. So i changed some sections from fully static page to “dynamic”, i added schema to them. I managed to do this on maybe 6 section, and all of them combined they had a lot of blocks in them. But after that i ALWAYS get this error when i tried to save in customize: “Online Store editor session can’t be published”. I tried clearing cache, i tried it on other device, on other browser, etc… nothing worked.

So i saw somewhere that there might be some limit of how much json you can write and that this may be the problem?

Something interesting i tried: So i had 4 empty textarea fields in Customize, and i wrote something in 3 of them and it still saved. When i tried to write something to the fourth field it said this error “Online Store editor session can’t be published”. Then i erased text from textarea 1 and again wrote something to textarea 4 and saved and it saved it.

Or another example: i tried removing 2 blocks from the section before and than i again could save all 4 teaxarea with text in them…

Is there a way to solve this?

1 Like
2

Did you ever figure this out? I’m having the same issue.

It’s definitely something about the specific theme I’m trying to save (as other themes/shops work fine), but I can’t tell which field Shopify doesn’t like.

3

Yeah i figured it out. As i said above the json file hit the max space limit, so i tried to remove as much text as possible from Customization fields, to the actual code, especially if you have some SVG code in customization.

4

Interesting! Pruning the JSON file did indeed resolve the issue in my shop. Thank you for the tip!

Strangely though .. my settings_data.json was only 22 KB, even less when minified .. which I thought surely wasn’t too large.
Alas, deleting all the “Presets” objects that came with the Debut theme got me down to 17 KB, and now I can use the theme customizer again.

I’m inclined to dig deeper to better understand the mechanics of this .. but I guess it’s a non-issue now that Theme 2.0 is the norm and the settings can be more “distributed”.
Anecdotally: I have a JSON page template well over 100KB (different store / Theme 2.0) and have never had issues saving it.

5

Strange indeed. If you do find any other solution later on, please do share :slightly_smiling_face: