Custom components created prior to Google Web Designer version 8.0.0 are no longer supported. Upgrade your custom components in order to use them.
What changed?
As of version 8.0.0, Google Web Designer uses components that follow the Custom Elements v1 specification. This standard is not compatible with the v0 specification previously used by Google Web Designer, and support for v0 components has been phased out as of July 2021.
Are published files affected?
Published documents will continue to work. These changes only affect the authoring in Google Web Designer, when creating or editing documents containing custom components.
Which components are affected?
Custom components require manual upgrade and will be grayed out and display a warning icon 
When you open a file in Google Web Designer, you'll see a list of any outdated components that are installed and used in the document.
Custom components on the stage will also display an icon that indicates they are unsupported.
The above warning and icon only appear for installed components.
All of the standard components that come pre-installed with Google Web Designer (such as the Swipeable Gallery and Tap Area) are automatically upgraded to use the newer v1 specification when possible, without any action on your part.
What happens to documents with outdated components?
Custom components that use the older v0 specification are no longer supported, and should be upgraded or removed from the document.
Once all outdated custom components in a document are upgraded, the standard components will be automatically upgraded to use the newer v1 specification.
How do I upgrade an outdated custom component?
Follow our upgrade guide. Knowledge of JavaScript is required.
How do I create a new custom component that follows the v1 specification?
The instructions for building a custom component and the example custom component have been updated to follow the newer v1 specification.
Do I need to do anything if a document doesn't use any custom components?
No action is needed for documents without custom components.
Can I use a mix of v0 and v1 custom components?
All of the components in a document must follow the same specification.