We Keep Coding

Cannot load user control design view in Visual Studio 2019

This is very strange. I have a custom UserControl called UIControl. That user control has another custom control (derived from Label control).
This worked OK for long time. Both at design time and at run time. However, now, I needed to edit that custom UIControl but the Visual Studio 2019 shows this error message:
This error means that the RealTime.DigitalClock is not found. As you see in the project, that control is not part of an external assembly, but the same assembly where UIControl is.
I have compiled and recompiled thousand of times and compilations finish perfectly. Even the application runs.
Furthermore, when I build the project, those user controls appear in tool box, but when I try to place it in any form, an error telling that the component could not be added and it will be removed from the tool box is shown.
I don't really know what is happening here. I have even closed and re-open VS 2019 but no avail.
Regards
Jaime

According to To prevent possible data loss in windows form c#, I suggest that you can do as the following steps.
First, Please find all the RealTime.DigitalClock related code in UIControl.designer and UIControl.cs.
Second, you can delete the above code.
Third, you need to rewrite the code you just deleted.
Finally, rebuild it and check if it works for you.

Visual Studio 2012 won't let me debug

I can't seem to be able to debug. When I try to, I don't get any build errors, and the layout changes to debug mode, but the windows never pops up. I have an orange bar at the bottom of VS, which I think is standard, but nothing happens after that. It's not just in the project I'm working on. I have started a new WFA and tried to debug without adding any code and the same thing happens. Anybody have similar issues?

I've encountered this before. Not sure what causes it, but generally it is one of a couple of things to fix it.
make sure you are building in debug and not release
close VS, go to the project's dir and delete the obj and bin directories. Reopen in VS and rebuild.
there is an option under tools - options - build (iirc) that allows for checking if source is same as code file. However, you should see a message in output window if this is the case.
on the project properties in the build (iirc) you can throttle the pdb file from full debug symbols to no pdb at all. If you are not the only person on the project check this setting still has full pdb enabled (low probability this got changed though)
make sure you're on the right platform that you are building to (x64 vs x32)
...lots more, but a starting place...
Addendum as per comment...
So, those messages are good. It is saying there are no problems (but it sounds like you already know that :) ). I would start with the general debug options you mention. Do this on a hello world app. That way you can troubleshoot the lowest common first. Here are my settings. Try to match them and see if that works. For example, I know "ask before deleting breakpoint" is irrelevant, but "break all processes when one process breaks" is important. So, I just added them all to make it easier to troubleshoot.
ALso, make sure you are getting a red dot here like so in your code in visual studio (I've seen instances where VS won't let you put this here):

Right click on the project
Click on the properties.
go to web.
Check the Box for Enable Edit and Continue .
Hope that helps :)

This is an issue with visual studio 2012. It doesn't ALWAYS show up. I've found that if you stop your program during debugging, or if you close the console window, this will almost always trigger.
However, letting it run to completion isn't enough either, sometimes this just happens.
Also you can build your application in debug mode, go to the output, run the program, and attach to that process. :P

Amazing answers already given but they dont help in the purpose. So here is my finding, no matter if i am late in answering, but it really works for me.
Even if you are developing a web app, just go to the website properties by right-clicking the project and then you see a "Web" tab on left as i have highlighted. Then just check the box saying "Enable Edit and Continue". Thats all you need to do. it works for me!

I had a similar problem, and solution was absolutely dumb. VS was confused with two instances of Internet Explorer in “Browse with” setting. So, I set Google Chrome (any browser) as default, and then set IE as default again. It deleted the other instance of IE (only one remained) and debugging was enabled.
Hope it help!

I had a similar issue.
I added up:
using namespace std;
and this solved the problem

For me, uninstalling the Redgate's Reflector plugin that had expired fixed it. I spent more than 4 hours uninstalling, rebooting, reverting to older code, etc etc..

When my default browser was changed to CHROME, I could no longer debug my User Interface. Setting IE back to the default browser fixed it. Alternatively you can attach the process plug-in during debug.

I had the same problem with my desktop application and as this forum says you should mark your project as a startup project, since visual studio has unmarked. It worked just fine for me an I believe it will help other people that may have this problem, since I believe you have finished this project.

One of my VB .NET Winforms projects wouldn't allow debugging.
This was due to the configuration manager set to 'Release' even though the toolbar dropdown indicated 'Debug'.
You need to select the mode dropdown and select the last option 'Configuration Manager' and ensure that the main project is set to 'Debug' and not 'Release'

Install Microsoft SSDTSetup.exe 450Kb and Close the SSDT tool during install. After installation open the SSDT tool and execute the script task and Component with breakpoint. Worked for me

try checking your output without debugging
Ctrl + F5
good luck

Why do I get an error 'Cannot resolve symbol <symbolname>' in ReSharper?

Using VS2008 and R# 5 I'm running into an odd situation, where on an aspx page I keep getting
Cannot resolve symbol 'symbolname'
But the code compiles and runs fine. While having a fix for this would be great, I'm just trying to figure out if I'm losing my mind.
The CodeFile directive and Inherits directives are fine. If I compile the app or just let devenv sit for a bit it'll go away, but as soon as I save the aspx [via ctrl+s] R# suddenly has trouble with the Inherits attribute and flips out on every method in the page (OnClick etc).
// Anonymized of course but otherwise intact
<%# Page AutoEventWireup="true" CodeFile="TestPage.aspx.cs" Inherits="TestPage" Language="C#" MasterPageFile="~/MasterPage.master" Title="Test Page Title" %>
This is mostly just a grievance, because since the code compiles it doesn't stop me from doing what I need.
I would post a bug report to the JetBrains site but first I would like to know I'm not alone. It could be my machine. Maybe when I roll to VS2010 in a couple weeks this will go away?

In Resharper you can disable inspection for that file with: Ctrl + Shift + Alt + 8.

So no final resolution yet. According to tech-support this is a known issue and is being researched. Final resolution undetermined at this time. If you're experiencing a similar issue, just hang tight. URL: http://youtrack.jetbrains.net/issue/RSRP-178681

Nothing worked for me until I followed this answer -- removing the related reference from the Project/References and then adding it again.

This worked in my case (Visual Studio 2015):
Go to Menu and select Options.
From the opened window, select ReSharper Ultimate (yours might be different edition) and click Suspend. That will basically suspend all the resharper features. Then click "Resume"
That should work. Otherwise, try to clean Resharper cache.

I just tried something odd and it worked. In your page directive, change the AutoEventWireup to false, SAVE the file, then change it back to true. It's some connection between the aspx file and the designer I think.

Try delete your .vs folder (hidden folder). It will reset config and cache of your solution

Suspend and and restarting Reshaper worked. Issue was resolved.

Why can't I debug my asp.net web app

When I add a breakpoint and hit F5 to run in the debugger (I am using my debug build), a dialog pops up telling my my web.config file does not have debug=true in it (which is does) and I get 2 choices a) run without the debugger or b) let visual studio update my web.config file. If I choose b) the web.config is updated badly and nothing will work. If I choose a) then the site appears and I can test it out, but no debugging.
I am an experienced developer, but I have never used visual studio and asp.net for web development before, so I am feeling rather frustrated by all the walls it is putting up to prevent me working.
So far I have not been able to use the debugger. Is there something totally obvious that I am missing? What would you check if it was happening to you?

Open web.config manually and make sure the following line is in there
<compilation defaultLanguage="c#" debug="true" />
Now you should be able to debug from VS. If this does not work I suggest that you recreate the project.
EDIT: perhaps from what you say it could be that web.config is screwed up, e.g.contains invalid xml, no closing tag for some element etc.

ligget78 said it first ^^
Try to delete completely web.config and let Visual Studio recreate it, if possible.

I agree with what was posted above, but another thing you can check is to, make sure that your page header in your aspx files does not disable debugging:
<%# Page Language="C#" MasterPageFile="~/default.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" Title="some title" Debug="false" %>
^^ that will turn off debugging.

In your project do a solution wide search for 'debug=' and if only one shows up then do a folder search. I've had it happen where there are multiple config files and this can cause problems.

If the debug=true is enabled then there is some problem in the Internet Application Server application. Try re-creating the web application and let Visual Studio create the web site.
Check also that the cassini web server is set up to be used as the debugging web server in the project properties.

This might be a dumb answer but it might also help.
I also encountered this problem on my setup. Though debug is already set to true, when F5 is hit, it won't still stop where the breakpoint is at.
I've solved it by chance when I close all the open IE then hit F5 again and that's how it work. (in my case, I placed the breakpoint at page_load for verification if it does stop at breakpoint).

ASP.NET controls cannot be referenced in code-behind in Visual Studio 2008

Ok, so, my visual studio is broken. I say this NOT prematurely, as it was my first response to see where I had messed up in my code. When I add controls to the page I can't reference all of them in the code behind. Some of them I can, it seems that the first few I put on a page work, then it just stops.
I first thought it may be the type of control as initially I was trying to reference a repeater inside an update panel. I know I am correctly referencing the code behind in my aspx page. But just in case it was a screw up on my part I started to recreate the page from scratch and this time got a few more controls down before VS stopped recognizing my controls.
After creating my page twice and getting stuck I thought maybe it was still the type of controls. I created a new page and just threw some labels on it. No dice, build fails when referencing the control from the code behind.
In a possibly unrelated note when I switch to the dreaded "design" mode of the aspx pages VS 2008 errors out and restarts.
I have already put a trouble ticket in to Microsoft. I uninstalled all add-ins, I reinstalled visual studio.
Anyone that wants to see my code just ask, but I am using the straight WYSIWYG visual studio "new aspx page" nothing fancy.
I doubt anyone has run into this, but have you?
Has anyone had success trouble shooting these things with Microsoft? Any way to expedite this ticket without paying??? I have been talking to a rep from Microsoft for days with no luck yet and I am dead in the water.
Jon Limjap: I edited the title to both make it clear and descriptive and make sure that nobody sees it as offensive. "Foo-barred" doesn't exactly constitute a proper question title, although your question is clearly a valid one.

The above fix (deleting the temp files) did not work for me. I had to delete the PageName.aspx.designer.cs file, then right-click my page, and choose "Convert to Web Application" from the context menu.
When Visual Studio attempted to rebuild the designer file, it encountered (and revealed to me) the source of the problem. In my case, VS had lost a reference to a DLL needed by one of the controls on my page, so I had to clean out the generated bin folders in my project.

try clearing your local VS cache. find your project and delete the folder. the folder is created by VS for what reason I honestly don't understand. but I've had several occasions where clearing it and doing a re-build fixes things... hope this is all that you need as well.
here
%Temp%\VWDWebCache
and possibly here
%LocalAppData%\Microsoft\WebsiteCache

Is the control that you are trying to reference inside of the repeater?
If so then you need to look them up using the FindControl method.
For example for:
<asp:Repeater ID="Repeater1" runat="server">
<ItemTemplate>
<asp:LinkButton ID="LinkButton1" runat="server">stest</asp:LinkButton>
</ItemTemplate>
</asp:Repeater>
You would need to do this to reference it:
LinkButton lb = Repeater1.FindControl("LinkButton1");

In my case, I was working with some old web site code, which I converted to a VS2008 solution. I encountered this same problem.
For me, the fix was to right-click the Web Sites project in the Solution Explorer and select Convert to Web Application. This created designer.cs files for all pages, which did not yet have these files before.

you will also find .net temp files which are safe to delete here:
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files

I observed this happens because of missing .designer.cs file. Following fixed this issue in my case (basically I had these files copied from VS 2005 web project to VS 2010 project): Right Click on .aspx file and select menu "Convert to Web site", this will create .designer.cs file and then it should work file.

In my case new asp controls I added to an existing were not being detected.
What worked for me was forcing a recompile by renaming an existing control to break the build eg: changing <asp:TextBox ID="txtTitle" runat="server" /> to <asp:TextBox ID="txtTitle2" runat="server" />
When I corrected the ID and rebuilt a new designer file was generated with the corrected ID and new controls.

right click on project name and select "Clean". then, check your bin folder if it has any dll remaining. if so, delete it. that´s it. just rebuild and every thing will work fine.

This can also happen if the Inherits property on the source page doesn't match the class name in the code behind. Generally speaking, this would probably only happen if you copy/pasted a .ascx/.aspx file and forgot to update it.
Example:
<%# Control AutoEventWireup="false" CodeBehind="myControl.ascx.vb" Inherits="myProject.myWrongControl" %>
The the code behind class:
Partial Public Class myControl

we cannot change the code when the application is running .To do so first click on the stop button on the top which will halt your application .now click on the button in design mode ,it will insert the code in .aspx.cs file ,then write the code in it

Check out your aspx file on errors, once I've faced with that problem

I had this happen a few times and it happened again today for a new reason. I normally run my project through IIS but needed to run it locally to debug. I normally run on port 80 in IIS and 81 in debug, but I had some settings in the web.config that used 80 so I just killed the site in IIS and switched the website to port 80 in the project settings. For whatever reason, this messed everything up and created the problem described in the OP. I started trying things one by one, including all the advice mentioned here, but switching the port back to 81 in the project settings is what ended up working.

For me, deleting/renaming the files in the following location worked:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\myvirtualwebsite\e331e0a9

Just to add my two cents with this problem.
The only thing from all the above that worked for me was the "Clean" and then delete anything left in the bin folder. Rebuild and all controls started working then.

FYI...I was having this problem too and I ended up fixing it by deleting the existing .designer.vb file, right-clicking on the project and choosing Convert to Web Application. It then showed the real "error" that was causing the GUI to crap itself. Turned out I had used the same name for 2 other labels but that wasn't being shown in the error list window. Once I renamed one of the 2 other labels it built fine and stopped giving me trouble.

You have to add
runat="server"
to each element in your page.