Error: Type argument 'double' doesn't conform to the bound 'Enum?' of the type variable 'T' on 'EnumProperty'. about flex_color_scheme

[Yukinosuke-Takada]

Also after upgrading to FCS 7.3.1 in pubspec, just to make sure, do:

@rydmike Had the same issue after upgrading Flutter. Can confirm, upgrading to 7.3.1 (was using 7.2.0 before) resolves this problem

[chandlery54]

Yes, thank you for the suggestions. It must have been cached on an old version like you said, because I thought I had already updated to the latest. But after cleaning and updating again it was resolved.

Thanks for your help.

[chandlery54]

It looks like it must be something to do with Flutter 3.16.+ cause I switched back to Flutter 3.13.3 (which I happened to have from another old project) and it ran fine without the error.

Framework • revision 2524052335 (4 months ago) • 2023-09-06 14:32:31 -0700
Engine • revision b8d35810e9
Tools • Dart 3.1.1 • DevTools 2.25.0

[rydmike]

Hi @chandlery54, thanks for filing the issue.

I have not seen or heard of this issue before.

The Xcode error seem to point to that you from the cached version are using FlexColorScheme (FCS) 6.1.2.

Due to breaking changes in Flutter framework SDK since the release of FCS 6.1.2, this version is not fully backwards compatible with Flutter 3.16.x. You need to use at least FCS version 7.3.x to get a version that is compatible with Flutter 3.16.x. I recommend to begin with assuring that the build is actually using the FlexColorScheme version 7.3.1.

Also after upgrading to FCS 7.3.1 in pubspec, just to make sure, do:

flutter clean
flutter pub get
flutter pub upgrade

So that no older version remains in the build cache.
The above should not be needed, normally flutter pub get is enough, but it has be known to happen that projects sometimes need it. Not related to FCS, but I have just seen it generally in some cases.