After Update to 0.20 from 0.19 the error Cannot assign to read only property 'defaults' of object '[object Object]' occurs
The release says that there a breaking change. Try that and see if the problem goes away. I got the same error but haven't tried the fix yet. https://github.com/artf/grapesjs/releases/tag/v0.20.1
Read full answer below βQuestion
GrapesJS version
- I confirm to use the latest version of GrapesJS
What browser are you using?
chrome
Reproducible demo link
none
Describe the bug
image.js :

Code of Conduct
- I agree to follow this project's Code of Conduct
Answers (3)
The release says that there a breaking change. Try that and see if the problem goes away. I got the same error but haven't tried the fix yet. https://github.com/artf/grapesjs/releases/tag/v0.20.1
Yes, as mentioned in the release note you have to switch from the old legacy API for custom component registration.
Thanks for reporting this, @Aventrue. The issue with After Update to 0.20 from 0.19 the error Cannot assign to read only property 'defaults' of object '[object Object]' occurs appears to be a race condition or state management timing problem. This typically happens when component lifecycle events a...
Related Questions and Answers
Continue research with similar issue discussions.
Issue #5378
Uncaught TypeError: Cannot read properties of undefined (reading 'Canvas') while dragging a component in Layer Manager Panel
GrapesJS version [X] I confirm to use the latest version of GrapesJS What browser are you using? Chrome v116.0.5845.97 Reproducible demo li...
Issue #5320
Upload Image or Asset is not triggering on File/Image selection
GrapesJS version [X] I confirm to use the latest version of GrapesJS What browser are you using? Chrome v114 Reproducible demo link none De...
Issue #5583
Can't set background:none in mobile version using styles panel
GrapesJS version [X] I confirm to use the latest version of GrapesJS What browser are you using? Edge last version Reproducible demo link h...
Issue #5385
GetDirtyCount() non deterministic after load
GrapesJS version [X] I confirm to use the latest version of GrapesJS What browser are you using? Chrome Reproducible demo link https://gith...
Paid Plugins That Match This Issue
Curated by issue keywords and label relevance to help you ship faster.
Loading paid plugin recommendations...
Check the open-source GrapesJS plugins on GitHub or run a quick search in our free catalog.
Browse free plugins βPremium plugins ship with support, regular updates, and production-ready features β save days of integration work.
Browse premium plugins βRelated tutorials
In-depth guides on the same topic.
Tutorial
How Much Does It Cost to Build a SaaS Page Builder in 2026?
How much does it cost to build a SaaS page builder in 2026? Explore realistic development costs, timelines, features, and how using GrapesJS can reduce
Tutorial
PageKit: the GrapesJS application you'd have to build anyway
A source-available Next.js app around the open-source GrapesJS core β publishing, custom domains, leads, checkout and a plugin loader.
Tutorial
UnStudio for GrapesJS: 4 Plugins to Build Better Visual Editors
Meet UnStudio, a new GrapesJS plugin studio with four tools, safer and better editor: Command Palette, Responsive Pack, Autosave & Restore, and Autofill
Browse Plugin Categories
Jump directly to plugin category pages on the marketplace.