Mendix Theme not compatible with Mendix 8.6.0

When I import my company’s theme as a UI Resource module to a Mendix 8.6+ project the autofill layout grid width automatically changes to -1. I tried creating a version of the theme for Mendix version 8.6.0, but this didn’t fix the issue. I also tried a different UI Resource and was met with the same problem. Any suggestions?
4 answers

Hi Jacob,

I suspect that your company’s theme is not based on (a recent version of) Atlas UI.

The new layout grid features depend on some new styles. That’s why we check the Atlas UI version to see if those styles are available. If the version number is old or non-existent, you will not get the new layout grid features.
Because you created an app that has already used the new features, but then imported another UI module, the version of the UI module / theme was either to old or non-existent.


To solve this, you can simply change the layout grid properties to make them valid, or ensure you got the right theme version and got the new layout grid styles.

The best way to do the latter is to (backup and) import the latest Atlas UI Resources module, and then merge your company UI module into the atlas UI module.


Another, not recommended way would be to place the 2 files below in your theme folder (with the same folder structure):




Hope this helps.


There seems to be a mismatch between pages that have been created using the new Layout grid feature. (see also the blog)

When using Mendix 8.6 in combination with Atlas UI Resources module 2.4 or higher, by default layout grid columns are set to ‘Auto-fill’ instead of a fixed weight. When opening a Page with such a layout grid in a project that does not use Atlas UI Resources 2.4 or higher, ‘auto-fill’ will be shown as ‘-1’.


I’m not sure what steps you performed to get into this scenario. But I would suggest to try one of these supported scenarios

  1. Upgrade/Use a project to Mendix 8.6 but don’t update Atlas UI Resources module to 2.4+: In this case the new Layout grid features will not be enabled.
  2. Upgrade/Use a project to Mendix 8.6 + update Atlas UI Resources module to 2.4 or higher. In this case the new layout grid features is enabled. Existing layout grids on existing pages will keep the manual / weight based settings. No changes required. To make sure that when your app has your own theme, you migrate the custom theme after the Atlas UI Resources module update too.



having the same issue, havn’t done any experimenting yet, but just letting you know, you’re not the only one.
will let you know how we fixed it.


Having the same issue with a atlas3 update, the solution for me was to download the Atlas core module again and replace the existing module on import.