Develop Reference

XF Android project does not build after adding Xamarin.Forms.Visual.Material nuget

I have a Xamarin Forms project and now I'd like to improve it with the new Visual / Material features.
On IOS, it works like a charm.
On Android I have strange problems: after adding Xamarin.Forms.Visual.Material nuget I get weird error messages and my project does not build:
\res\values\values.xml(6): error APT0000: Attribute "statusBarBackground" already defined with incompatible format.
\res\values\values.xml(2): error APT0000: Original attribute defined here.
\res\values\values.xml(10): error APT0000: Attribute "layout_anchorGravity" already defined with incompatible format.
\res\values\values.xml(2): error APT0000: Original attribute defined here.
\res\values\values.xml(17): error APT0000: Attribute "layout_insetEdge" already defined with incompatible format.
\res\values\values.xml(2): error APT0000: Original attribute defined here.
\res\values\values.xml(17): error APT0000: Attribute "layout_dodgeInsetEdges" already defined with incompatible format.
\res\values\values.xml(2): error APT0000: Original attribute defined here.
\res\values\styles.xml(2): error APT0000: Error retrieving parent for item: No resource found that matches the given name 'Theme.MaterialComponents.Light.DarkActionBar'.
\res\values\styles.xml(2): error APT0000: No resource found that matches the given name: attr 'materialButtonStyle'.
\res\values\styles.xml(2): error APT0000: Error retrieving parent for item: No resource found that matches the given name 'Widget.MaterialComponents.Button'.
\res\values\styles.xml(2): error APT0000: Error retrieving parent for item: No resource found that matches the given name 'Widget.MaterialComponents.Button.OutlinedButton'.
\res\values\styles.xml(2): error APT0000: Error retrieving parent for item: No resource found that matches the given name 'Widget.MaterialComponents.TextInputLayout.FilledBox'.
\res\values\styles.xml(2): error APT0000: No resource found that matches the given name: attr 'boxCollapsedPaddingTop'.
I use Visual Studio 2017 Professional on Windows, I don't use any prerelease nuget.
Xamarin.Forms version is 3.6.0.293080.
Minimum Android API level is 21, target is 28, and compiled with 28.
Xamarin Android support libraries version is 28.0.0.1.
I tried the usual tricks (delete bin, obj dir, restart Visual Studio, run it in admin mode, delete Xamarin app data...) but neither helped.
The same thing happens if I create a new project from schratch, and don't do anything with it, just add visual.material nuget to the Android project.
Do you have any suggestions? Thanks a lot!

I had the same issue a few days ago where I first had TargetFramework set to Android 8.1, installed same packages and later changed it to Android9 and installed a new package.
The Xamarin.Forms.Visual.Material requires Android 9 to be set in Android project options and you previously had 8.1 configured and installed nuget packages for Android 8.1.
If you still use old packages.config like me to add NuGet packages, make sure you always see same monodroid string in hint path in the csproj and don't mix 81 with 90 and always have monoandroid90.
<Reference Include="Xamarin.Forms.Visual.Material , Version=3.6.0.293080, Culture=neutral, processorArchitecture=MSIL">
<HintPath>..\..\packages\Xamarin.Forms.Material.3.6.0.293080\lib\monoandroid90\Xamarin.Forms.Material.dll</HintPath>
</Reference>
After changing TargetFramework to 9, open Package Manager Console and run
Update-Package -Reinstall -IgnoreDependencies
to let VS update the packages.config and csproj.

I found this answer on github:
Migrating Package.json File to PackageReference to resolved problem.
1 - Click right on packages.config in Android Project
2 - Click on Migration Package.config to PackageReference
3 - Accept
4 - Run Project
Ref: https://github.com/xamarin/Xamarin.Forms/issues/5828
I also updated references with Nuget, done a clean, removed obj and bin fonder, and then Build.

No resource found when I change build variants from debug to release

I am facing this issue from few weeks when I change build variants from debug to release it will give me the following error:
Error:(213, 37) No resource found that matches the given name (at 'background' with value '#color/themeGray').
For every resource file that image or string already present in respective folder if anyone know about this issue please help.

Xamarin Android - No resource found error

I get the following error in xamarin Android:
SeverityCode Description Project File Line Suppression State Error No resource found that matches the given name (at 'value' with value '#integer/google_play_services_version').
Please help me resolve this issue.

No resource found that matches the given name in Manifest

I'm getting this error when trying to build the application. The xml editor did not highlight both error as missing. As the file/string are already there.
android-apt-compiler: [XXX]
D:\private\xxx\android\XXX\src\AndroidManifest.xml:35: error: Error:
No resource found that matches the given name (at 'icon' with value
'#drawable/ic_launcher').
android-apt-compiler: [XXX]
D:\private\xxx\android\XXX\src\AndroidManifest.xml:233: error: Error:
No resource found that matches the given name (at 'value' with value
'#string/FacebookAppID').
The project structure is like this:
ProjectFolder
|-external_lib
|-src
|-src (actual source)
|-res
|-...
I can confirm that both file is already in the project. As I use IntelliJ, I could just Ctrl + click then it open those files for me. However, I'm still getting this error.
I checked with both Google and SO. Most of the issues were about not having the files or storing in different folders. Which I can ensure that it is in the right place alongside hundred other files and strings.
Another issue is about % sign in strings.xml. I tried searching for "%" and nothing is found in the file.
Shutting down IDE and reopen it doesn't help, nor rebuilding the project. How could I get the app to build?

Look for any error message during the resource compilation.
Sometimes, if you have resource filenames containing illegal characters (such as underscores or uppercase letters), the whole process fails almost silently, and the IDE can't find any resources anymore.
I'm not sure that it's what is happening in your case, but I did eventually encounter such issues...

Running the android in-app billing example aplication

This will probably sound silly but I have no idea how to make the application work.
tutorial for in-app billing
Just like the tutorial says I downloaded the package, I found the files. The problem is there's no project file and I can't get it to work in eclipse.
Anyone used the example app?

I've used it successfully...what seems to be the problem? Once you download the files, bring the project into Eclipse by select "Newn Android Project", "Create project form existing source" and the "Finish." From there, follow the directions regarding changing the package name, etc...

As far as I can determine, the sample Dungeons in-app billing project that I downloaded via Android SDK Manager, does not even compile (this seems to have been fixed, see my comments later in this message..).
As a check, I ran a find command to search for one of the missing resources:
/cygdrive/k/android-sdk-windows/extras/google/play_billing $ find . -name '*.xml' -exec grep edit_payload_title {} \; -print
android:text="#string/edit_payload_title" />
./res/layout/edit_payload.xml
/cygdrive/k/android-sdk-windows/extras/google/play_billing $
As you can see, the resource #string_edit_payload_title is referenced once, but never defined in any of the xml files..
Description Resource Path Location Type
error: Error: No resource found that matches the given name (at 'background' with value '#color/screen_background'). item_row.xml /Dungeons/res/layout line 20 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'background' with value '#color/screen_background'). main.xml /Dungeons/res/layout line 20 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'prompt' with value '#string/select_item'). main.xml /Dungeons/res/layout line 52 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'text' with value '#string/buy'). main.xml /Dungeons/res/layout line 47 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'text' with value '#string/edit_payload_title'). edit_payload.xml /Dungeons/res/layout line 25 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'text' with value '#string/edit_payload'). main.xml /Dungeons/res/layout line 58 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'text' with value '#string/items_for_sale'). main.xml /Dungeons/res/layout line 34 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'text' with value '#string/items_you_own'). main.xml /Dungeons/res/layout line 64 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'text' with value '#string/recent_transactions'). main.xml /Dungeons/res/layout line 80 Android AAPT Problem
error: Error: No resource found that matches the given name (at 'textColor' with value '#color/error_message'). main.xml /Dungeons/res/layout line 28 Android AAPT Problem
** UPDATE ** I just downloaded it again and it seems to be resolved. At least, it builds and deploys now.. And the string definitions seem to be in place now..
/cygdrive/k/android-sdk-windows/extras/google/play_billing $ find . -name '*.xml' -exec grep edit_payload_title {} \; -print
android:text="#string/edit_payload_title" />
./res/layout/edit_payload.xml
<string name="edit_payload_title">Edit the developer payload associated with this purchase</string>
./res/values/strings.xml