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WebView2: Multiple instances of same application need to launch the same browser control

Problem
I recently replaced a System.Windows.Forms.WebBrowser-based control with one that relies on Microsoft.Web.WebView2.WinForms.WebView2 instead. This has been working well, except that my users want to have 2 instances of their application running at once, with both instances occasionally having that WebView2 form open at the same time. When they try this, one of the two instances fails to load the WebView2 control until the other one is closed.
Learned / attempted so far:
I've found WebView2 to be extremely finicky, so I've looked into alternatives like CefSharp, but haven't wanted to dedicate time to implementing them until I know they can solve the problem. So far as I can tell, CefSharp and WebView2 do very similar things as far as launching a Chromium-based browser, rendering to a WinForms control.
This blog post (read: advertisement) for paid alternative DotNetBrowser indicates that
You can initialize and use several Chromium engines simultaneously with different configurations [in DotNetBrowser], which is not possible in CefSharp.
I'm wondering if this same limitation applies to WebView2, and is the cause of my users' inability to have 2 instances of that same form loaded at once.
Context
I'm supporting an ancient desktop CRM that's set to be retired in favor of a modern alternative, but in the mean time, the old standard needs to integrate with new processes we're bringing in. One of those new processes is a web page from an external service that our call center users enter data into, then expect the CRM to pull entered data out of the web page.
The part of their process I did not know about is the 2-instance bit from above: they're used to being able to copy-and-paste from one embedded browser window to the other.

#Poul Bak in the comment on the question had it right: providing settings that differ per-instance of the application fixed the problem.
The setting I changed per-instance was the path of the user data folder: I was able to pass different values for the userDataFolder argument of the CoreWebView2Environment.CreateAsync method, branching based on a variable that holds different values between the instances that my users are running.

Anyway to deal with weird errors while my .net program running?

I made a program, which works fine on my PC without any errors, it also works fine on some office PCs, but it crashes without any describable error on customer's PC and some others.
Crashes are completely random, sometime it may crash and sometimes not.
Crashes are not related with any actions, sometimes it may crash when they just look at the program and wait for crash.
Customers send me this beautiful screens and want me to solve this.
There you see common error reporting dialog, but not info about Exception.
My program uses Unity Web Player running in WebBrowser control. It's always run in background on the hidden tab which becomes visible when needed.
Any ideas how to handle such errors?

I think you should first ensure that the environment at your place and that of your customers are identical.
Maybe there're dll or other programs installed at your place (Unity web player as you mentioned for example) or anything in your Registry that may differ.
Else there's no point in getting error on one PC and not on another.
Make sure all dll are well deployed
Check your registry,
Ensure that all related programs are well installed

.NET 4 WebBrowser hangs

I am using .NET 4 and trying to use the desktop authentication for the StackApps site via the web-browser control (WPF and/or WinForms) to develop a NNTP Bridge for accessing StackOverflow (https://stackapps.com/questions/4215/stackapp-nntp-bridge-for-accessing-stackexchange-forums-like-stackoverflow).
It seems that the login cannot be done, because the web browser hangs up, after the page from "StackExchange Login" is displayed.
I use the following URL:
https://stackexchange.com/oauth/dialog?client_id=1736&scope=no_expiry&redirect_uri=https://stackexchange.com/oauth/login_success
It works in the normal IE browser, but not in a WinForms or WPF window... Does anyone know what the problem is?
It is simple to repoduce:
Create a WinForms-Project
Add the "WebBrowser" control to the dialog
Double-Click on the Form1
Add the following code
private void Form1_Load(object sender, EventArgs e)
{
webBrowser1.Navigate("https://stackexchange.com/oauth/dialog?client_id=1736&scope=no_expiry&redirect_uri=https://stackexchange.com/oauth/login_success");
}
Start the application
Login by pressing the "login with Stack Exchange" account symbol
A new page gets loaded; it is displayed correctly, but you cannot enter your login name; the window hangs...
The same happens, if I use WPF-App and the WPF-WebBrowser-Control... it seems that it is stuck in an endless-loop in JavaScript...
Any hint on how to solve ths problem?
Or is it possible to debug the JavaScript in the WebBrowser-Control???

Fixing WebBrowser Control
I also had the issue of the WebBrowser control handing when trying to login.
Although requesting a token in IE (11) works, I found that IE itself also hangs when I put it in IE 7 emulation mode. This suggested to me that my previous attempt to make the WebBrowser control use a newer version had failed.
I found this article, Web Browser Control Specifying the IE Version, which suggests that for 32 bit applications in 64 bit mode, you need to set a different registry value.
So now, I've added two values in the registry:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION
and
HKEY_CURRENT_USER\Software\Wow6432Node\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION
In both of them, I added a DWORD value named 'MyExecutable.exe' (where MyExecutable is the actual name of my executable). The value for each of them is 9000 which will work for IE9 and above. Watch out when using RegEdit to test this, it will default to hexadecimal instead of decimal. Also, make sure it is a DWORD value, not any other type.
This seems to do the trick. I can now run the application, go through the login process, and eventually I am redirected to the url specified by me, which I can then capture using the OnNavigate event of the webbrowser control.
Remaining issue
It doesn't really work perfectly. The first time I was redirected to some OpenID page as well, but at least the form didn't hang. With subsequent attempts, apparently the login (which succeeded before) is remembered and I get the message "Navigation to the webpage was cancelled" with a link to refresh the page. When I click that link, I am immediately redirected to the redirect_url I specified when requesting the login form. At least that part works, and I get an actual access_token and an expiry time, so for now I'm happy.
Update: After some testing, it turned out that the previous login was remembered. That causes the request uri to direct to the redirect_uri immediately. I used the OnBeforeNavigate event to detect this, but it isn't fired in this case. I now linked the NavigateComplete2 event, and that one is triggered in this scenario.
Fix for .NET?
I think for .NET the solution should be the same: add the executable (and MyExecutabl.vshost.exe as well, for debugging purposes in Visual Studio) to the first key. If it's a 32 bit executable running on 62 bit Windows, you might also need to add it to the second key, although I'm sure if that rule applies to .NET as well. I don't do C# on a daily basis, and I'm trying to get it to work in Delphi first, but if I find time to test this in C# I will post the update here.
In the end, it would be nice if the actual issue would be solved, and the JavaScript would work in IE7 mode as well, but at least this seems to be a proper work-around.

Unfortunately, I'm not a JavaScript developer, so I only could try to explain you how to debug a JavaScript that executes in the WebBrowser control.
This approach is for the Microsoft Visual Studio, I don't know if Delphi can provide similar functionality.
Enable Script Debugging (both Internet Explorer and Other) in Internet Explorer settings.
Disable Friendly HTTP messages in Internet Explorer settings.
Enable Display a notification about every script error in Internet Explorer settings.
From Visual Studio, start your WebBrowser hosting application without debugging (i. e., Ctrl + F5).
In Visual Studio, go to Debug → Attach to Process… and select your application in the list.
Hit the Select… button to the right of Attach to: field and choose Script code.
Hit the Attach button. Visual Studio starts the script debugger.
In your application, navigate to the deadlocking page by pressing the Login with Stack Exchange account symbol.
Go to Visual Studio and press the Pause button on the debugging toolbar.
Now you can look into your script code and investigate the code itself, the call stack, the variable values and so on. You can set breakpoints too. Perhaps you can then find the place where the script hangs. As I said before, I'm not a web developer and cannot help you with this…
Update:
I guess I can propose you a working solution.
My investigation shows that the WebBrowser hangs when it renders the content in the IE7 mode (what is the default mode even if you have IE10 in your system). You should force it to switch into IE9 mode. In IE9 mode, the page renders well and does not cause the script to stuck in an endless loop.
You can switch your WebBrowser to the IE9 mode using one of the following methods:
Define the global browser emulation mode for your application in Windows registry.
For 32 bit OS, go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION.
For 64 bit OS, use HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION.
In this node, create a new DWORD parameter called YourApplicationExeName.exe with a value 9000 (0x2710). You can create another entries for your *.vshost.exe executables, if you want this to work in Visual Studio debug mode.
Manipulate the source for the WebBrowser to switch it in the IE9 mode.
This will be more complicated. You need to alter the <head> tag of the html document adding a new <meta> tag preferably as a first element: <meta http-equiv="X-UA-Compatible" content="IE=9"/>.
This will cause the WebBrowser to switch its mode on document rendering. Since you can't change the compatibility mode after the document is rendered, you could use a proxy as a source for your WebBrowser, so this proxy will add the header.
I`ve successfully tested this with the 1st approach, and the second one should work too.
Hope that helps!

Project + Properties, Debug tab, tick the "Enable native code debugging" option. Ensure that you've got the Microsoft Symbol server enabled (Tools + Options, Debugging, Symbols), I know you do :)
You can now use Debug + Break All and see what's going on inside the browser. Do so repeatedly to get the lay of the land. You'll see that Javascript is executing (jscript8.dll) and constantly forcing the layout engine to recalculate layout, never getting the job done.
Browsers in general are vulnerable to Javascript that's stuck in an endless loop. A regular browser tends to put up a dialog after several dozen seconds to allow the user to abort the JS, but WebBrowser doesn't have that feature. Nor does it have the dev tools so debugging the JS isn't going to be a great joy either. This is going to be difficult to get fixed.
You might consider using the OAuth 2.0 api instead. Notes on usage are on this web page. Exactly how to integrate that with WebBrowser is a bit murky to me, I don't have a key to test this. Find help for this at the Stackapps site. You are probably not the first SE api user that ran into this problem.

"Unable to start program" error for web project

I have a Silverlight project that we use internally that I wrote - and since we've not had any need to work on it, it's been a while since I've opened the project. I opened it up this morning and everything is fine in terms of building, but whenever I try to debug I get the following error:
Unable to start program "http://mymachinename/mywebsite/index.aspx"
Of course, running it in Firefox works fine but no symbols are loaded. Running without debugging still throws the same error but IE loads up anyway...
Navigating to the website in IE works fine - SL app opens up, loads data etc etc, all looks good
I've Googled this all morning (usually quite good at finding info) and been through all the questions on SO and I can't figure out what's going on - there doesn't seem to be any messages in the event log, there are no messages in any VS output window, the w3wp just terminates immediately after starting (probably due to there being an error trying to open IE). I've tried reinstalling IE, cleaning/rebuilding, using local dev server, creating a new web project, turning on/off settings in IE9 etc etc
Nothing seems to make a difference - anyone got any experiences of this and has fixed it without doing one of the things I've already done? Any other suggestions?
Thanks in advance!
UPDATE
Just to be clear in case anyone asks - I get this problem when creating a new web project - i.e. everything I said I'd tried (above) didn't change the behaviour. It showed the same error no matter what I'd done so far (that includes a NON SL web project)
I've also tried attaching the debugger to w3wp that is running (the standard IIS process) and I can't seem to get it to debug (no symbols are loading), but that might be another issue altogether. I'm going to look at that next and maybe if I figure that out it might lead to fixing this issue
UPDATE 2
Debugging in Firefox works - I attached to w3wp with no success, then realising my stupidity (SL being a client side app!) I attached to the plugin-container.exe that FF runs its plugins in. This works. I can probably do the same for IE and just attach to IE, but why won't it start up from VS?! hair pull
UPDATE 3
Just in case anyone asks, the default browser is set to IE in VS. Also I've managed to debug by attaching to IE, it just won't start IE from within VS - annoying but I can live with it for now. If anyone does have a suggestion though, feel free...

For anyone's information in case they have this same problem, it ended up being that the port I was running my site on was also running a SharePoint site!
I created a new site on port 81 and used that for dev - not sure what setting on the other site caused the issue but it ended up working on port 81.

Why does my new .Net 4.0 EF application randomly lock up?

I have recently rolled out a new ASP .Net application. This application uses .Net 4.0 and the Entity Framework 4. It is a "basic" CRUD application. I almost exclusively used the EntityDataSource for Data Access.
The users have reported "ocassional freezing" of the application (they all use IE 8). If the user closes his browser and starts back up, the app is fine. It happens maybe once or twice per day total, usually to the heavy users. (So, I have been leaning toward memory leack or some other kind of resource limitation.)
Until just a little while ago, I have never seen this happen. It dosn't leave anything in the Event Log on the client PC nor Server. Also, there is nothing in the IIS error logs or the SQL logs.
A little while ago, I finally got it to happen. I was switching all of my EntityDataSources to use a single Object Context per page. I downloaded the EF Profiler (which seems to be a great product) and it pointed out that I am using multiple object contexts on many of my pages, due to the fact that many of them have more than one EntityDataSource. So, I was cleaning all this up and testing each page, when lo and behold....IE stopped loading pages!
At first, the page started loading slowly (and this was a page that I had already modified to use a single Object Context, so although I still believe I need to implement this "singleton" pattern throughout all my pages, I guess it isn't the culprit! Anyway..), then at some point I received:
Message: Sys.WebForms.PageRequestManagerTimeoutException: The server request timed out.
Still, nothing in the Event Log. I also checked the IIS web logs and I don't see anything, but they are pretty tough to read with the naked eye, I may have to download a parser to make sure there is nothing in there.
Anyway, I decided to start up another window and navigate to my app, and sure enough that window worked fine, no problems. I went back to the windows that stopped responding, refreshed it, waited... went to the home page of my app (which is basically just some static html.. and nothing.. ). Next, I opened a new tab in the window that is currently frozen and that tab works fine. So, I go back to the window that can no longer load pages from my app and try some other web sites.... espn.com loads fine, msn.com loads fine, I then enter the URL for my app home page (and tried some other pages in my app) and NOTHING. IIS doesn't even log the attempts in its Log Files (its like IE has just decided not to do anymore "gets" for my localhost!). Finally, after waiting for a while (while I was typing this post) I now have this error message in that window:
Internet Explorer cannot display the webpage. What you can try: The problem can be caused by a variety of issues, including: BLAH BLAH BLAH...
So, I jump back to that window and it can still browse Internet sites just fine. But, once again when I try to go to any of the pages in my app, I get NOTHING (spinning blue circle in the tab). So, once again I start a new tab in that same browser and I can browse around my application just fine.
What has my app done to this browser instance that will no longer let it load any of its pages (in fact, it seems like it isn't even doing a GET on any of the apps pages, since there is nothing new in the IIS logs...except for when I load the pages in these other tabs and/or browser windows that work fine, so the logging is still working...)? I will be forever indebted to the person that can help me figure this out. I am not sure it will do much good, but I am going to leave this browser window up on the chance that someone can tell me some things to try to diagnose this problem. It feel like I am THIS close to figuring it out. I finally have a window up that is misbehaving. I am afraid to close the window or do a new build on the app until I get some good input on things to try....
I should add that when this happened to me, I was running on my local PC, so I was the only user and only had one window open to the app..
Although, I am completely stumped!

We had the same issue and seemed to fix it by adding the following JavaScript to all pages with ajax:
window.onunload = abortRequest;
function abortRequest() {
Sys.WebForms.PageRequestManager.getInstance().abortPostBack();
}
I hope this helps!

sounds like a request just takes too long to execute. A web-browser is only allowed to keep two concurrent connections to a single webserver unless you utilize http pipelining (which isn't well supported anyway). However, My experience is that this is per browser, not per tab.
This is why nothing shows up in your logs, because your browser never initiate a request because it is waiting for the page to finish loading before it can fetch another page. I would start looking into the last request initiated before the lockup, it is probably that page that locks for some reason and never finishes.
ASP.NET utilizes only one thread as long as all request are sequential. As soon as you fire up two request simultaneously, a new thread is initiated (Init() on HttpApplication is invoked), and that can cause intermittent errors if you do funky stuff on Init().
If you think this is related to EF, you might read up on how to avoid locking in multi-threaded environment (because a web application is very much multi-threaded however this usually kicks in a production environment).

Ugh, I feel your pain - I hate these types of issues. Here's my divide-n-conquer process when something like this is happening (adapted somewhat to your case):
Step 1 - Environment Visibility
Get yourself set up so you can roughly see inside your systems. Set up Performance Monitor, and add a couple of important counters (IIS Current Requests, ASP.NET Current Requests, SQL Server - Active Transactions). The idea here with the "active requests/transactions" counters is you want to find out which part of the system is holding on to the request.
Additionally, add counters for total request time in IIS and the DB (so you can see it climbing as something is hanging on).
On your client PC, set up Fiddler.
Step 2 - Reproduce Issue
Usually at this point, the application realizes you can see it and starts behaving perfectly. ;) Stop and make sure you can still reproduce the issue.
Step 3 - Take the DB out of the equation
Create 4 pages in your application:
Static HTML file (.htm) that will NOT go through the ASP.NET runtime engine. This is your baseline for raw IIS.
ASPX page with no tricks (no database access, no processing, just a simple page that ASP.NET can spit out)
ASPX page with one simple database call (of some size, maybe do a single big query or something)
ASPX page with some complex transactions (multiple queries, etc)
Step 4 - Reproduce and measure
Since this issue will probably be pretty obvious once you can see it, find the bottleneck with your performance counters and Fiddler. Your issue sounds like you could have an intermittent connectivity issue (either between client and web server or web server/SQL), especially if IE is giving you the "page cannot be displayed" error, but you should see that in Fiddler. On the server side, you should see one of those performance counters hanging.

well, sounds like the app is waiting for a database operation to complete but is locked, probably because of another operation.
Try using the SQL profiler to trace the activity, and isolate what processes are running for a long time.
You can differentiate the requests using the SPID column in the trace view, it contains a unique ID number for each session from your App.

I have new information regarding this issue.
The application uses Integrated Authentication. This causes every reqest to come back (twice) with access denied, before IE send the credentials.
I can't help but wonder if this is what could be causing the "time outs".
I implemented an Ajax "Loading" animation on every page that prevents the user from clicking a button until the previous request is completed and that has GREATLY diminished the amount of "freezes" the users are experiencing.
Although, it still happens somewhat often.