BlankPage constructor cannot initialize components

Question

I'm starting learning XAML and I add some code to my BlankPage application. And suddenly a constructor which is initializing a component:

    public BlankPage()
    {
        this.InitializeComponent();
    }

Stop working. I've got now that error:

'BlankApplication.BlankPage' does not contain a definition for 'InitializeComponent' and no extension method 'InitializeComponent' accepting a first argument of type 'BlankApplication.BlankPage' could be found (are you missing a using directive or an assembly reference?)

Honestly I didn't do anything, I didn't even look at this part of code and now it doesn't work.

Screenshot:

Problem solved, I didn't change custom application name in xaml code. — r9s, Apr 22 '12 at 09:38
Please post solution as an answer so it can help others too. — jv42, Apr 23 '12 at 07:39
Hi - Exactly the same thing happened to me, working through the MS "Metro" tutorial. "I didn't do anything"... except start the project with the wrong name ("WindowsBlogViewer", instead of "WindowsBlogReader"). The moment I cut/pasted XAML code from the tutorial (code with the *correct* namespace: "using:WindowsBlogReader") I got the "xyz.BlankPage' does not contain a definition for 'InitializeComponent" error. The fix was to recreate the project with the correct namespace ("WindowsBlogReader"). — paulsm4, May 30 '12 at 00:46
This is ideal solution for this problem. http://stackoverflow.com/a/7730022/2149459 — Arjun, Feb 28 '17 at 21:59
@r9s You may want to mark the response from `nuriselcuk` as the `Answer` since he, I think, has correctly described your issue and has provided a correct solution. If you mark his response as an `Answer` it would help other readers (like me) of your post better. Thank you. — nam, Jun 05 '19 at 20:37

score 14 · Answer 1 · answered Jan 03 '13 at 21:18

Just to give a bit more information on how to fix this (since this explanation is a bit on the vague side)..

This issue (for me) was caused because I changed the namespace in the code after I created the project. In order to fix this issue I had to make some changes in a couple of locations:

1: In App.xaml I had to change the following:

<Application
  x:Class="New.Namespace.App"

2: In MainPage.xaml I had to change the following:

<Page
  x:Class="New.Namespace.MainPage"

You will also want to make sure that you change the 'namespace' line in your App.xaml.cs as well as your MainPage.xaml.cs.

Finally, you will also want to make sure you update the Project Entrypoint in the Package.appxmanifest to point to "New.Namespace.App".

My problem was an unseen error shown at the bottom of the MainPage.xaml page. — 27k1, Feb 13 '16 at 11:57
I added a ContentDialog in the wrong project in my solution, and when I moved it, I didn't change the namespace in the XAML. This tipped me off to the problem. Thanks! — dex3703, Mar 01 '17 at 22:21

score 3 · Answer 2 · edited Oct 13 '16 at 12:25

3

This happens when you change a namespace for a class, you must do the same inside the XAML file.

There are two places inside the XAML file with the old namespace.

edited Oct 13 '16 at 12:25

Axel Isouard

1,498
1
24
38

answered Oct 13 '16 at 11:08

long.h

31
1

score 3 · Accepted Answer · answered Aug 08 '18 at 12:56

If your Main class's namespace is different than .xaml file's x:Class attribute, you will get this error. For instance;

Your MainPage.xaml.cs;

    namespace UWPControls
    {
        /// <summary>
        /// An empty page that can be used on its own or navigated to within a Frame.
        /// </summary>
        public sealed partial class MainPage : Page
        {
            public MainPage()
            {
                this.InitializeComponent();
            }
        }
    }

Your MainPage.xaml;

<Page
    x:Class="UWPControls_Different.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UWPHelloWorld"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
</page>

You're going to see the error until changing x:class to the;

x:Class="UWPControls.MainPage"

Your solution is best for the problem at hand (issue posted by the `OP`). Nice explanation related to the issue. I think `OP` tried to explain it later but probably could not do it as well as you did - and hence he deleted his response as show below. The `OP` should mark your response as an `Answer` so others can benefit from it. — nam, Jun 05 '19 at 20:33

score 2 · Answer 4 · answered Apr 29 '19 at 14:38

2

For me, the project was inside solution with other projects. When suggestions here did not work, a simple unloading and reloading the project from solution did the trick and fix all errors (with rebuilding of course).

answered Apr 29 '19 at 14:38

Izik

746
1
9
25

score -1 · Answer 5 · edited Sep 22 '17 at 18:19

-1

My Solution: For my "SomePage : ContentPage", I changed the XAML properties:

Generator (Custom Tool): From MSBuild:Compile to MSBuild:UpdateDesignTimeXaml
BuildAction: From Page to Embedded resource

Using Visual Studio 2017 Enterprise 15.3.4

edited Sep 22 '17 at 18:19

Quality Catalyst

6,531
8
38
62

answered Sep 22 '17 at 17:45

Fábio Lupo

1
2

score -3 · Answer 6 · edited Nov 27 '17 at 20:16

-3

Problem solved. Cause: I forgot to also change custom application name in xaml code. Solution: I have changed application name in XAML, now it works well.

edited Nov 27 '17 at 20:16

brett

744
5
15

answered Apr 23 '12 at 13:58

r9s

227
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-1. If you're going to answer your own question, you should answer it with the same quality as you would answer someone else's question. – Sinaesthetic Nov 27 '15 at 01:12
By changing it. I didn't before and that was the problem. – r9s May 31 '16 at 09:56
This actually helped me. I edited the phrasing of the answer to make it clearer, but it pointed out the right issue. You English purists stop the down-voting already :) – brett Jan 28 '18 at 18:36

BlankPage constructor cannot initialize components

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