How to Migrate Mendix 7 to 8

Marcel Groeneweg
Jan 22 · 4 min read

The migration from Mendix 7 to 8 is not that hard, but there are a couple of things worth mentioning though. This blog post is an addition to the documentation page: Moving from Desktop Modeler Version 7 to Studio Pro 8. In this blog, I pinpointed some subjects and own experiences to keep in mind when migrating your Mendix apps from Mendix 7 to Mendix 8.

Keep a copy of the Mx7 project

Sometimes it can help to have the original Mx7 project available too, so be sure to create an export and open it so you can compare after conversion. Also very nice to have for checking userlib / Java JAR issues.

Appstore modules — userlib content

Many Appstore modules have been updated to support Mendix 8. Quite often these modules also come with updated versions of their dependencies.

· If you just download all Appstore modules, you will end up with Java JARS for the same function but with different version numbers. So you should clean up the userlib folder of your project first.

· If you did not include any Java functionality of your own, you can clean userlib before downloading all Appstore modules again. This will make sure you have the latest, and only, version of the dependencies.

· If you do have custom Java functionality, you need to check which JARs are necessary for those Java actions to work correctly. Compare with your Mx7 copy where necessary.

Theme migration

The theme migration has been really well documented. If your current theme is already based on Atlas, migration is not that difficult, but pay close attention to the migration instructions and the changes to the DOM made in Mendix 8.

For a custom theme that is older than Atlas, you will need to base your theme on Atlas 2.0.0 or higher to prevent theme issues in Mendix 8. That can require extensive rework, especially if the current theme has a complex company style.

The DOM changes in Mendix 8 really are quite an improvement and make customization easier, so it is well worth the effort.

Theme error

After migration of the project to Studio Pro 8, you will have an error that you are using a modified Atlas theme. Even after you migrate your theme, the error will not go away. Just right-click it and then you can remove it. (That’s new, usually, errors go away when you make changes, but there is just no way for Studio Pro to detect you’re done so you will be the judge of that.)

Modified theme error message

Missing Phone layouts

As of Atlas UI 2.0.0, the phone layouts have been renamed, causing a lot of errors in your project if you referenced that layout. There is a simple fix for this, the example is for Phone_Default:

· Find HybridPhone_Default

· Rename it to Phone_Default. Mendix will show a popup mentioning there are existing usages. Confirm the dialog

· Rename it back to HybridPhone_Default. Do not undo the change, that would not work.

Errors about design properties

(This part has been edited at 10–2–2020 to reflect the fix Mendix made for design property issues during migration)

Before Mendix 8.6 you could get errors like one of the following:

  • CE6083, Property Align Self is not supported by your theme. Check theme\settings.json.
  • CE6085, Unknown option Center align as a column for property Align content.

As of Mendix 8.6, with Atlas UI 2.4.1, Studio Pro will convert design properties that were renamed or had their values renamed. You will see one or more of the following messages:

CE6087 Design properties have been renamed in your theme and need to be updated. Right-click to see more options.

You can right-click one of these message and convert all design property values at once.

Be careful if you had created design properties of your own, make sure these are back in place before you do this, otherwise these might be mistaken for stuff that’s no longer there. Although that is a really different error, I advise to apply your design properties first.


Don’t let the migration hold you back. I’ve done a few already without too much hassle. The theme migration is also well worth the effort. All in all, Mendix 8 is a great release.

Mendix Community

The community-sourced publication for low-code

Marcel Groeneweg

Written by

Mendix MVP and Certified Expert. Focus on Mendix native mobile apps and widgets.

Mendix Community

The community-sourced publication for low-code

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