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Sometimes when I'm editing page or control the .designer files stop being updated with the new controls I'm putting on the page. I'm not sure what's causing this to happen, but I'm wondering if there's any way of forcing Visual Studio to regenerate the .designer file. I'm using Visual Studio 2008

EDIT: Sorry I should have noted I've already tried:

  • Closing & re-opening all the files & Visual Studio
  • Making a change to a runat="server" control on the page
  • Deleting & re-adding the page directive
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It's it ridiculous that in 2012 Visual Studio still doesn't have a context menu item to regenerate designer files from source files? It's akin to not being able to rebuild a corrupt DLL. I don't understand it.. Especially with external source control and external editors you leave Visual Studio crippled. Waste of money, if you ask me. I'm actually trying to regenerate resource file designers. I managed to get edit it regenerated, but it's through obscurity... Augh!!!1 –  bambams Nov 21 '12 at 15:06

37 Answers 37

up vote 195 down vote accepted

If you open the .aspx file and switch between design view and html view and back it will prompt VS to check the controls and add any that are missing to the designer file.

Also, you can try to right click on the as(c/p)x and select "Convert to Web Application". When this is done you should see that you now have a *.Designer.cs file available and your controls within the Design HTML will be available for your control.

PS: This should not be done in debug mode, as not everything is "recompiled" when debugging.

Some people have also reported success by deleting the .designer.cs file and then recreate an empty file with the same name.

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I found that changing from debug mode to release mode dig the trick for me, Thanks –  Chris Jun 22 '10 at 16:06
"Convert to Web Application" was just what I needed! Thanks. –  Chad Jan 30 '12 at 22:01
Just wanted to say that I was having the same error and tried everything on this page, with nothing working. Turned out I was missing a ">" close tag on a div that had runat="server". Running VS-2008. –  Ber53rker May 16 '12 at 14:07
To make "Convert to Web Application" appear, first you need to delete the Designer.cs file BY RIGHT CLICKING the aspx file in Solution Explorer and selecting delete. This worked for me in VS 2010. –  DeveloperDan May 16 '12 at 21:02
VS2013 has the Convert to Web Application under the Project menu. Just no longer in the context menu. –  Dennis Burton Jul 21 at 19:35

Well I found a solution that works, though I don't really like it. I had to delete the .designer.cs file then recreate an empty file with the same name. When I went back in and saved the aspx file again, the designer file was re-generated.


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This did not work for me. Now I have an empty file and all of the code behind does not work!!! Rebooting... –  Dining Philanderer Mar 19 '09 at 20:25
This worked for me. I made sure to delete the original, create a new designer.cs file with the same name, close the new file, modify the .as(p/c)x file slightly to force a save, then it was all good. –  TJB Apr 15 '09 at 21:43
Thank you thank you thank you ... I was going crazy with this problem in my project - wasted a whole day on it before finding your answer! –  Shaul Behr Aug 2 '09 at 17:08
if you have a view compile error, it won't come back. Generally thats why it stops regening in the first place. You need to turn on view compile to see it, which is not straight forward. –  DevelopingChris Feb 11 '10 at 13:53

I use the following method which works everytime:

  • Select all of the code-in-front (html markup etc) in the editor of the aspx/ascx file.
  • Cut.
  • Save.
  • Paste.
  • Save.


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There is another possibility: You may have an error in your .aspx file that does not allow Visual Studio to regenerate the designer.

If you switch to Design View, it will show the control as unable to be rendered. Fixing the control (in my case it was an extra quote in the properties) and recompiling should regenerate the designer.

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+1 thank you - that helped me! –  Shaul Behr Aug 4 '09 at 9:34

I recently saw that I was having the same problem. Visual Studio 2010 was refusing to update the designer file.

As it turns out, VS doesn't modify the designer file for a page that uses CodeFile (run off of pages) instead of CodeBehind (DLL). This is true no matter how many times you close VS, reload the project, re-create the control(s), or modify a file. Nothing would prompt VS to regenerate the designer. It's as if it doesn't create the designer file for CodeFile pages but does require it to be there.

I changed it to CodeBehind and saved the page. The designer file updated immediately. Then I just changed it back and everything was still golden. This behavior seems to be new with VS 2010 / .NET 4.0 as VS 2008 by default didn't suffer from this.

It's this part:

<%@ Page Language="vb" AutoEventWireup="false" CodeFile="YourPage.aspx.vb" Inherits="YourPageClass" %>

Change CodeFile to CodeBehind, save, and then revert.

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This solution worked for me when nothing else would. Very strange that it started suddenly. –  Tridus May 6 '11 at 17:22
despite the number of up votes this is [IHO] correct answer ... –  krul Aug 5 '11 at 15:05

the only way I know is to delete the designer file, and do a convert to web app. However when you do this, it usually pops up with the error, as to why it didn't auto-regen in the first place, its usually a control ref that isn't declared in the head of the page.

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This worked perfectly. Should be the accepted answer imho –  Garry Harthill Feb 10 '10 at 16:47

Most of the solutions here don't work if you're running Visual Studio 2013 and possibly 2012. Microsoft probably introduced some optimizations to make the IDE snappier, consequently they've reduced the number of cases that trigger the code generator. The following scenarios that used to work no longer do:

  1. Delete the aspx or ascx file -- No longer checks for this case
  2. Cut all the content and repaste into the aspx or ascx file -- No longer works, no change in the references
  3. Convert to Web Application -- Option no longer available
  4. Arbitrarily changing content on the aspx/ascx file -- No longer works (see 2).

The solution is surprisingly simple, but it's slightly cumbersome. In order to trigger the code generator, change something that would require the designer.aspx.cs to be generated. Changing content that doesn't affect code, such as a CSS style or adding text, won't trigger the code generator. You must change a referenced control. Here's how to do it:

In the ascx or aspx change the ID of the control

<asp:HyperLink ID="MyLink" runat="server" NavigateUrl="~/Default.aspx" Text="Home" />


<asp:HyperLink ID="theLINK" runat="server" NavigateUrl="~/Default.aspx" CssClass="tab" Text="Home" />

Go to the ascx.cs or aspx.cs and make sure you rename all references to "MyLink" to "theLINK" as well. Save and do build and the you should be good to go.

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3. 'Convert to Web Application' is made available in the 'PROJECT' menu if an appropriate file is selected. –  WynandB Jul 22 at 7:24

(The following comes from experience with VS2005.)

If you edit an ASPX page while debugging, then the codebehind doesn't get updated with the new classes. So, you have to stop debugging, trivially edit the ASPX page (like add a button or something), then click Design View, then delete the button. Then, your designer files should be updated.

If you are having a different issue with VS2008, then I can't help.

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My experience is that if you want to do like in this article, like stated above.

Your markup file (aspx/ascx) has to include the CodeBehind="MyPage.aspx.cs" attribute or else it won´t work. I blogged about it here.

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+1 Fixed it for me. My page was missing this attribute –  Ralph Lavelle Apr 27 '10 at 11:38

I often found that copy/pasting caused this behaviour for me. Most cases can be solved by editing the ID of a server control (just add a character, then delete it).

Also remember that control inside things like Repeaters aren't visible in the designer file.

And yes, there are cases where you need to do the delete-the-file magic listed above - but the name-change solution will work most of the time.

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That's the kind of error that i have many times. If you copy HTML from one page to other and have controls with runat="server", controls will be renamed to avoid conflict. However, if you paste inside "html comment" tags <!-- whaterver --> , control id's will not be changed, and any conflict will stop designer file to be regenerated, because there are two controls with the same ID. That's because controls inside html "comments" tags are also created. ;) –  tomasofen Nov 30 '13 at 20:10

When you are in design view, right click on the screen and hit refresh.

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Convert to Web Application did not work for me.

Deleting designer.cs and pasting a blank designer.cs did not work either.

But yes this worked:

  1. Select all(Default.aspx)
  2. Cut
  3. Save Default.aspx
  4. Paste
  5. Save Default.aspx

Done. New designer.cs generated. :)

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  • Select-all in the designer file and delete everything in the file, leaving it blank and then save
  • Select-all in the ASPX/ASCX file and cut everything and then re-paste it back
  • The designer file should have regenerated the code
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This did not work for me. –  Zack Peterson Jan 26 '09 at 16:21
This worked for me! I also saved the .aspx file after cutting everything out. Pasted back in, saved, and my (previously blank) designer file was fully populated. –  DaveD Mar 18 '12 at 20:46

Here is wat i experienced , Select the website folder right click in the Solution Explorer, select Convert to Web application for all the aspx file a designer file will get generated.


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Just to add to the long list of answers here - I've just run into this issue in VS2010 (SP1) with an .aspx file. I tried adding and removing standard ASP controls (which has worked in the past) but in the end, I had to remove one of the runat=server lines from an existing control (and save) to force the designer file to regenerate.

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I've encountered the same problem for years now, working in Visual Studio 2008. And I've tried every "solution" on StackOverflow and dozens of blogs, just like I'm sure all of you have. And sometimes they work, and sometimes they don't, just like I'm sure all of you have encountered. And apparently it's still an issue in VS2010 and VS2012.

So finally, a couple of months ago, I decided enough was enough, and over a few weeks I built a tool called "Redesigner" that generates .designer files. It's open-source under the BSD license, with the source code available on SourceForge — free to use, free to steal, free to do anything you please with. And it does what Visual Studio fails to do so often, which is generate .designer files quickly and reliably.

It's a stand-alone command-line tool that parses .aspx and .ascx files, performs all the necessary reflection magic, and spits out correct .designer files. It does all the parsing and reflection itself to avoid relying on existing code, which we all know too well is broken. It's written in C# against .NET 3.5, but it makes pains to avoid using even System.Web for anything other than type declarations, and it doesn't use or rely on Visual Studio at all.

Redesigner can generate new .designer files; and it offers a --verbose option so that when things go wrong, you get far better error messages than "Exception of type System.Exception was thrown." And there's a --verify option that can be used to tell you when your existing .designer files are broken — missing controls, bad property declarations, unreadable by Visual Studio, or otherwise just plain borked.

We've been using it at my workplace to get us out of jams for the better part of the last month now, and while Redesigner is still a beta, it's getting far enough along that it's worth sharing its existence with the public. I soon intend to create a Visual Studio plugin for it so you can simply right-click to verify or regenerate designer files the way you always wished you could. But in the interim, the command-line usage is pretty easy and will save you a lot of headaches.

Anyway, go download a copy of Redesigner now and stop pulling out your hair. You won't always need it, but when you do, you'll be glad you have it!


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I've found a way to solve this problem without changing any code or running commands like "Convert to Web Application" - and it's simple too!

What I found was that restarting Visual Studio often solves the problem, but sometimes it doesn't. In those cases, if you close Visual Studio and then delete all content in the "obj" directory for the web project before you open it again, it has always worked for me.

(when started again you just add a space and remove it again and then hit save to have the designer file properly regenerated)

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Delete the designer.cs file and then right click on the .aspx file and choose "Convert To Web Application". If there is a problem with your control declarations, such as a tag not being well-formed, you will get an error message and you will need to correct the malformed tag before visual studio can successfully re-generate your designer file.

In my case, at this point, I discovered that the problem was that I had declared a button control that that was not inside of a form tag with a runat="server" attribute.

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This is a bug in the IDE; I've seen it since VS 2003. THe solution is simple though.

Save your files. Completely exit the IDE (make sure the process stops, task mgr.)

Reopen the solution, dirty the markup, save. Fixed.

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I had two problems... outdated AJAXControlkit - deleted the old dll, removed old controls from toolbox, downloaded new version, loaded toolbox, and dragged and dropped new controls on the page (see http://www.experts-exchange.com/Programming/Languages/.NET/Visual_Studio_.NET_2005/Q_24591597.html)

Also had misspelling in my label control (had used 'class' instead of 'cssclass').


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If you are like me and you add old .ASPX files to a more recent project. You are probably going to forget some of the controls used on the page.

If so, first thing, if there are multiple files you are installing; Fix one at a time first.

When you compile, fix errors generated. They will probably be the same errors in all the files.

Next, if you have Designer files, delete all of the inserted - designer files. Next, make sure there are not any other errors when you compile, other than the designer files.

Finally right click your web project and click on Convert to Web Application. This will insert the designer files you need.

These are the absolute best steps to fix the issues.

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This can also happen if you update the namespace and don't update the namespace in the designer file. Fix: Update the namespace in the designer file too.

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Another thing which worked was -

  1. Manually delete & then Create a designer file in filesystem.
  2. Edit Project file.
  3. Add code to include designer
    Eg: <Compile Include="<Path>\FileName.ascx.designer.cs"> <DependentUpon>FileName.ascx</DependentUpon> </Compile>
  4. Reload Project
  5. Open as(c/p)x file in design/view mode & save it.
  6. Check designer file. Code will be there.
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  1. replace your custom tag with a invalid tag name. Save it
  2. restore the invalid tag name back to custom tag name. Save it. Then you will be prompted to checkout the *.designer.cs files(or silently modify the designer.cs) and produce correct variable of custom tag control.
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I had this problem and for me, I had a space in one of my ID values for one of my controls. I took the space out and the designer file regenerated itself.

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In my case I was just missing a register TagPrefix at the top. Somehow the previous dev worked without having this in there?

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I have had this issue before. I usually just hit enter to add a line and then wait for the plus/minus to show on the html page and the designer should add what you need. I have also had to close the project and reopen it to get it to work.

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I've had this problem a lot, and just did again. I tried fixing it using these suggestions, and nothing worked. I finally found that I had the 'Title' attribute in the page header twice(I added to the end, not realizing that VS added a blank Title="" to the beginning)-- removing the extra attribute caused VS2008 to re-generate the designer file... I hope VS2010 fixes this problem, letting us know why the designer file generation isn't happening...

-- Derek

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Apart from all the good answers already given, I'd like to add to @johan-leino's great answer. In my case, for some arbitrary reason, the CodeBehind attribute was omitted from the @Page directive/.aspx file. Likewise, it might be worthwhile to check the CodeFile attribute for @Control directives/.ascx files (obviously in conjunction with an Inherits attribute in both cases).

Depending on the exact scenario and reason required to 'force' a regenerate of .designer.cs, one could also try to format the document (potentially indicating a parsing error) before (quick) saving (regardless whether there were any changes or not) and check the Error List for warnings.

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In my case, it was fixed when I added a CodeBehind to the @Page section.

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