resource attr/colorPrimary (aka com.companyname.handlepdfmauiapp1:attr/colorPrimary) not found.

Question

resource attr/colorPrimary (aka com.companyname.handlepdfmauiapp1:attr/colorPrimary) not found.

Jonathan 170

Hi,

How to resolve it? I got the issue even if I've rebuilt it.

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Answer 1

Hello @Jonathan ,

Thanks for your question.

The error resource attr/colorPrimary not found occurs because MAUI's Android platform uses Material Components themes by default, which require colorPrimary, colorPrimaryDark, and colorAccent to be explicitly defined in your resource files.

You can refer to these following steps:

Create or update Platforms/Android/Resources/values/colors.xml:

Platforms/Android/Resources/values/colors.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#512BD4</color>
    <color name="colorPrimaryDark">#3700B3</color>
    <color name="colorAccent">#03DAC5</color>
</resources>

Create or update Platforms/Android/Resources/values/styles.xml:

Platforms/Android/Resources/values/styles.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="MainTheme" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
</resources>

Select both files in Visual Studio and verify Build Action = AndroidResource, otherwise Android will not include them in the resource compilation step.
Delete bin/ and obj/ folders, then do a full rebuild solution

If the issue persists, please provide the following details so I can investigate further:

The full build error log
Your .csproj file content

Please try and let me know if it works. I'd be happy to investigate further.

I hope this information was helpful. If so, please consider following the guidance to provide your feedback. Thank you.

Answer 2

attr/colorPrimary and attr/colorPrimaryDark are built‑in Android theme attributes. The error

resource attr/colorPrimary (aka com.companyname.handlepdfmauiapp1:attr/colorPrimary) not found

means the build cannot resolve that attribute in the current project.

To resolve it in a .NET for Android / MAUI app, ensure that:

The attributes are referenced from the correct namespace
- When using Android framework attributes in XML, reference them via the Android namespace, for example:
```
     <item name="android:colorPrimary">@color/your_primary_color</item>
     <item name="android:colorPrimaryDark">@color/your_primary_dark_color</item>
```
- Do not declare colorPrimary or colorPrimaryDark as custom attributes under your app’s package; they already exist as framework attributes.
The app theme is based on a Material/AppCompat theme that defines these attributes
- In styles.xml, ensure the app theme inherits from a Material/AppCompat theme that supports colorPrimary and colorPrimaryDark, for example:
```
     <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
         <item name="colorPrimary">@color/your_primary_color</item>
         <item name="colorPrimaryDark">@color/your_primary_dark_color</item>
     </style>
```
- Then set this theme in the Android manifest or in the MAUI project’s Android configuration.
Clean and rebuild after fixing XML
- After correcting the theme and attribute references, run a full clean and rebuild so that the generated Resource.Attribute.ColorPrimary and Resource.Attribute.ColorPrimaryDark constants (with IDs 16843827 and 16843828) are correctly picked up from the Android framework.

If any custom library or layout is still referencing @attr/colorPrimary without a compatible theme, update that library/theme to use a Material/AppCompat base theme so the attributes are available.

References:

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resource attr/colorPrimary (aka com.companyname.handlepdfmauiapp1:attr/colorPrimary) not found.

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