Bug 56538 - AppDelegate.cs: The type of namespace name 'App' does not exist in the namespace (are you missing an assembly) - .NET Standard
Summary: AppDelegate.cs: The type of namespace name 'App' does not exist in the namesp...
Status: RESOLVED FIXED
Alias: None
Product: Live Player
Classification: Xamarin
Component: Mobile App iOS ()
Version: 1.0.253
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
: 58505 ()
Depends on:
Blocks:
 
Reported: 2017-05-17 02:25 UTC by Andrew Hoefling
Modified: 2017-12-24 15:33 UTC (History)
13 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description Andrew Hoefling 2017-05-17 02:25:04 UTC
VS4Mac Version : 7.1.0.583
Xamarin Live Player Version : 1.0.253

When attempting to run my Xamarin.Forms project I get the following error:
`AppDelegate.cs: The type of namespace name 'App' does not exist in the namespace (are you missing an assembly)`


Things I have tried
--
- Verified all my references are correct
- Removed references from my PCL (net standard 1.6) and added it back in
- Added fully qualified reference to App() instead of using `using` statement

Let me know what other information you will need to confirm the bug.
Thanks!
Comment 1 Jan Göltenboth 2017-05-25 21:14:44 UTC
I'm facing the same problem in an android project. The Android project references a netstandard 1.4 project instead of a PCL. When I use a PCL library then xamarin live works fine. When I switch over to netstandard the error message appears as you already mentioned (emulator and native deployment works). This issue prevents me from using the live view as I cannot use PCL libraries due to shared code based on netstandard 1.4.
Comment 2 James Montemagno [MSFT] 2017-05-30 18:01:27 UTC
So, it looks like specifically the issue is around using .NET Standard libraries with Xamarin.Forms. 

PCL and Shared projects work today, but will validate this.
Comment 3 Frank A. Krueger 2017-05-31 00:11:02 UTC
I can figure out what's going on with a sample project.

There have been a lot of fixes to the player since 1.0.253 so it's possible this has already been resolved.
Comment 4 James Montemagno [MSFT] 2017-07-31 19:10:29 UTC
Can confirm that it is an issue with .NET standard types.
Comment 5 James Montemagno [MSFT] 2017-08-04 22:13:42 UTC
*** Bug 58505 has been marked as a duplicate of this bug. ***
Comment 6 Vinícius Rodrigues Filenga 2017-11-10 18:50:55 UTC
Is there any relation of this error with APP heap size? This is necessary to use the onesignal SDK but makes it impossible to deploy to any virdual device and possibly to use the Live player. Can anyone confirm that?

Many on my classes are not

Errors list:
(1,1): error: Resource identifier 'HomePage.xaml' has already been used in this assembly
(1,1): error: Resource identifier 'PartnerSelectingPage.xaml' has already been used in this assembly
(1,1): error: Resource identifier 'ProfileView.xaml' has already been used in this assembly
(1,1): error: Resource identifier 'HomeView.xaml' has already been used in this assembly
(1,1): error: Resource identifier 'NotificationsView.xaml' has already been used in this assembly
The type or namespace name 'App' could not be found
The name 'App' does not exist in the current context
Comment 7 James Montemagno [MSFT] 2017-11-29 00:57:25 UTC
Latest versions now support .net standard libraries.
Comment 8 tim.rossiter99 2017-12-09 01:19:35 UTC
James, 

I do not think this issue is resolved. 
I made a Xamarin.Forms project with a .NET Standard Library and I am getting the same error on all 3 of my projects; Android, iOS, UWP. 
This is happening before I have edited any code. 
But on an olded project with a PCL library theres no error. 


Error	CS0246	The type or namespace name 'App' could not be found (are you missing a using directive or an assembly reference?)
Comment 9 Paul Willies 2017-12-24 15:09:58 UTC
I also have this issue with current builds of Xamarin Live Player. I can push the project directly to the device - that works fine. But when I try to use the "Player" device, I get a host of build errors, including the one mentioned by Tim Rossiter. Here's the distinct errors I get:

---
The type or namespace name '<various>' could not be found (are you missing a using directive or an assembly reference?)

Resource identifier '<various>.xaml' has already been used in this assembly

The name '<various>' does not exist in the current context

Dependent project <NETStandard>.csproj failed to build, using old version.
---

All errors show as being on line 1 - which is also interesting.
Comment 10 Paul Willies 2017-12-24 15:33:21 UTC
I'm wondering if this should be created as a New ticket - since this one is closed... Also wondering if this is because we are now linking to .NET Standard 2.0 - no longer 1.x...