
Hi @Aurelie C,
Thank you for posting in this community.
Here are a few things you can try to resolve this issue:
1.Schema Reference: Ensure that your JSON schema reference is correct. The latest schema URL should be:
{
"$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json"
}
2**.Validation Error**: The Monaco Editor used in SharePoint’s formatting tab sometimes throws validation errors that don’t actually prevent your formatting from working. You can often ignore these errors if your formatting appears to be working correctly.
3.Syntax Check: Double-check your JSON syntax. You can put your JSON code into some JSON code editor, and it will automatically find syntax issues with your JSON code.
4.Excel-style expressions are not supported on SP 2019. You need to use the AST(Abstract Syntax Tree) version of the JSON from the sample repository on SP 2019.
You can find more examples of SharePoint 2019 in this link below.
https://github.com/SharePoint/sp-dev-list-formatting/tree/master/column-samples
5.If the problem persists, please tell me the type of your column, the full JSON code, and the styling effect you want to achieve.
This will help me analyze and solve your problem better.
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