topic Re: Custom theme not appearing in Experience Builder (Developer Edition) despite successful build in ArcGIS Experience Builder Questions

Custom theme not appearing in Experience Builder (Developer Edition) despite successful build

MaximeDemers — Tue, 10 Mar 2026 19:47:16 GMT

Hello everyone,

I'm having trouble getting a custom theme to show up in the Experience Builder interface.

I have downloaded the demo-theme from https://github.com/Esri/arcgis-experience-builder-sdk-resources/tree/master/themes and installed as is in the client/your-extensions/themes/demo-theme folder

I use the original manifest.json:

{ "name": "demo-theme", "label": "Demo Theme", "type": "theme", "thumbnails ": [], "font": { "fontFamily": "Avenir Next", "color": "#484848" }, "version": "1.19.0", "exbVersion": "1.19.0", "author": "Esri R&D Center Beijing", "description": "This is a demo theme containing all customizable theme variables.", "copyright": "", "license": "http://www.apache.org/licenses/LICENSE-2.0", "translatedLocales": [ "en", "zh-cn" ], "isNewTheme": true }

When doing npm run, I see that webpack found and build the theme successfully in client/dist/themes/demo-theme.

Everything seems fine so far but that demo-theme does not appear in the experience builder client.

I have try to restart the client and server, erase cache, run in private mode, etc without success.

What could be the cause of this problem? Is there something I'm missing?

Experience builder is v1.18 and nodejs v22.19

Thank you

Re: Custom theme not appearing in Experience Builder (Developer Edition) despite successful build

MaximeDemers — Wed, 11 Mar 2026 12:27:52 GMT

I had try many things and finally found out that, in the manifest.json, the isNewTheme property must be set to false to make it appears.

It seems there is something wrong with how experience builder handle this property, at least in version 1.18

Re: Custom theme not appearing in Experience Builder (Developer Edition) despite successful build

JeffreyThompson2 — Wed, 11 Mar 2026 12:28:00 GMT

I think I see the problem. Themes were majorly re-designed at 1.19 and the current documentation is not fully compatible with how Themes worked in 1.18.