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Source files mismatch when stepping into .NET Framework code

Motivation
I'm trying to track down an exception thrown by .NET Framework when opening connection to Access mdb database file. I'm not opening the database connection directly but rather use one of DevExpress Xpo facilities (XpoDefault.GetDataLayer(...) to be precise) which internally attempts to create connection to provided mdb database file. That attempt fails somewhere deep in .NET Framework code and exception is thrown.
Exception has System.Data.OleDb.OleDbException type and is very vague about the problem source. Message says "Unspecified error". ErrorCode is -2147467259 (NativeCode is 0). There is to little information to find out why database connection cannot be created. I thought that maybe going deeper into .NET Framework code would reveal something important about the failure.
Problem
Source files mismatch when stepping into .NET Framework internals. Inconsistent execution flow.
Description
My application is targeting .NET Framework 4.6.1 x86 platform and built in Debug (Release does not change anything). Visual Studio Enterprise 2019 v16.6.3 is the IDE I work with. Of course I've read all I could about debugging into .NET Framework first but it did not help to solve my problem.
What I have done so far? I have successfully download DevExpres PDBs and sources. No problem with that - I can follow execution down into DevExpress internals (which IMHO confirms that overall debugging setup is rather correct). It also seems that .NET Framework PDBs are correctly loaded from Microsoft servers during debugging. I think that Visual Studio Debugging settings are also fine (as far as I'm aware).
All goes well until I need to step into OleDbConnection.cs file which gives the following message:
The problem is that I have all .NET sources available from https://referencesource.microsoft.com. All (including updates) from version 4.5.1 up to latest 4.8.
No matter which one I choose - I'm always getting same message about not matching source file version. When I ignore the message and decide to use the source file anyway, it shortly turns out that inconsistency is real. Instead of tracking the source code execution I'm stepping over comments or execution flow simply does not make sense and clearly the presented source code is not in sync with what is going on.
Ok, that's it. I could not get any farther. Am I doing something wrong? Where to look for .NET Framework sources which would match the executing modules and allow to discover origins of the exception I'm getting?
Update #tgolisch
Code which gives an exception:
Session Session;
ReflectionDictionary reflectionDictionary;
string connectionString;
...
Session = new Session(XpoDefault.GetDataLayer(connectionString, reflectionDictionary, AutoCreateOption.SchemaOnly));
Connection string used in XpoDefault.GetDataLayer(...) call:
"Provider=Microsoft.Jet.OLEDB.4.0;Password=;User ID=Admin;Data Source=C:\\Svn\\trunk\\Apps\\bin\\Debug\\DbFile.mdb;Mode=Share Deny None;"
XopDefault.GetDataLayer(...) is the call which fails and throws exception.
Update #Perry Qian-MSFT
I did exactly what you suggested with no success. There was no improvement at all. However, I have made a fair progress after disabling optimizations of system assemblies as described here. With optimization turned off, tracking of .NET Framework internals becomes feasible. No more random jumping or stepping over comment lines.
However, it is not a full success yet, because I'm still getting messages about mismatch between executing modules and the source code file versions.
I have also noticed that even though my app has .NET Framework 4.6.1 as a target it still uses version 4.8 of system modules during execution:
That suggests I should use .NET Framework 4.8 sources when stepping into framework internals. But wait - I have tried all sources I could get with the same mismatch problem.
What can also be seen is that there is more than one version of system assemblies being run with the app - 4.8.4110.0 and 4.8.3761.0, which suggests that different sources might have been used to build them.
Yet still, no matter which sources I take there is always a message about source mismatch at some point.
Considering that assembly optimization problem has been resolved, which framework sources should I use now to have them in sync with running modules?

Source files mismatch when stepping into .NET Framework code
Please reconnect your DB Access database to refresh your database in case there are some build errors in the db layer.
Besides, please follow these suggestions to troubleshoot your strange issue:
1) Tools-->Import and Export Settings-->Reset all settings-->..General to reset all debugging settings.
2) then, close VS, delete .vs hidden folder under solution folder, bin and obj folder.

Xamarin iOS native linking failed for grpc.core

I've been attempting to make grpc work (ssl http2) on Xamarin Forms and after some pain I managed to get it to work on Android using Grpc.Core. However I couldn't get iOS to compile. Working through this problem I was trying to get anything grpc related to work on iOS, and eventually found the grpc experimental xamarin demo, HelloworldXamarin. Found here:
https://github.com/grpc/grpc/tree/master/examples/csharp/HelloworldXamarin
I downloaded the solution, but when I try to compile it I get the following errors:
Error Text:
Native linking failed, undefined symbol: operator delete(void*). Please verify that all the necessary frameworks have been referenced and native libraries are properly linked in.
Native linking failed. Please review the build log and the user flags provided to gcc: -LC:/g/examples/csharp/HelloworldXamarin/packages/Grpc.Core.2.23.0/build/Xamarin.iOS10/../../native/ios/universal -lgrpc_csharp_ext -force_load C:/g/examples/csharp/HelloworldXamarin/packages/Grpc.Core.2.23.0/build/Xamarin.iOS10/../../native/ios/universal/libgrpc_csharp_ext.a -LC:/g/examples/csharp/HelloworldXamarin/packages/Grpc.Core.2.23.0/build/Xamarin.iOS10/../../native/ios/universal -lgrpc -force_load C:/g/examples/csharp/HelloworldXamarin/packages/Grpc.Core.2.23.0/build/Xamarin.iOS10/../../native/ios/universal/libgrpc.a
linker command failed with exit code 1 (use -v to see invocation)
For the warning regarding not being able to find libgrpc_csharp_ext.a, I verified that the file was there.
There appears to be some issue with native linking, which I am very unfamiliar with. I'm using nearly the latest Visual Studio (well, 16.5.3), a mac build host with latest OS and XCode updated to latest. Didn't make any changes to the files pulled from git. I only just started working with Xamarin iOS this week, so everything should be in a fairly "default" state.
What could be wrong with my setup/system that makes this not work? I understand that this is an experimental feature still, but I can't tell if I've done something stupid or if there's been some change in something (like XCode? or it needing VS 2017?) that makes this no longer work? Is anyone else able to get this example to compile?
I've also tried newer versions of the grpc nuget packages and that only resulted in more errors.
Ultimately I'm trying to get latest Grpc.Core to work in iOS on Xamarin.Forms, though I have very little experience working with iOS. If there are issues with the latest versions of XCode/Visual Studio/Grpc.Core that are causing this, I'm willing to try to work through them, if someone can point me in the right direction.

It is not at all related to your versions or something that you did or didn't do.
First for some theory:
If someone wants to use Objective-C libraries or CocoaPods packages in their Xamarin project, they will need to create a binding library for this. Take it as some sort of a "bridge" between the native implementation and the later exposed C# code that you can use. You can learn more about the binding from the official documentation here and more specifically here.
To sum up the info - after the bindings have been created, you see a .lib or .a file. This is exactly what they have done - exposed some native code into the libgrpc_csharp_ext.a. Unfortunately, there are some bindings that are not correct. This is exactly what you are seeing here - the aftermath of an incorrect binding.
Looking a bit into the project I got to the following conclusions:
There is an open issue from May 2019 about this - https://github.com/grpc/grpc/issues/19172
Unfortunately, the issue is still active and there is no movement there.
I have confirmed that after version 1.21 (incl.) the build is not working. For now, you can downgrade to version 1.20.1 (last known to work). I have successfully built the solution with it. Please review the changelog and release notes for this specific version (if any) so that you know if it will fit your needs.
Basically, you have 2 options:
Downgrade to the last good version in order to use it;
If you want to use the latest version either wait for the issue to be fixed, or fork the repo and help with the fixing.
If you want to see their build script and help fix the issue, you can start from here.
Another useful resource is this video from the official Xamarin channel.

Azure Function App Build Error - Multiple Assemblies with Equivalent

I have not touched my Azure functions in several months. I came back yesterday and made changes which I then pushed to Github. The CI integration failed to build my changes however, because of the error below:
CSC : error CS1703: Multiple assemblies with equivalent identity have been imported: 'D:\home\site\repository\packages\System.Xml.ReaderWriter.4.3.0\lib\net46\System.Xml.ReaderWriter.dll' and 'D:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\Facades\System.Xml.ReaderWriter.dll'. Remove one of the duplicate references. [D:\home\site\repository\DataModel\DataModel.csproj]
It seems like maybe this library now exists on the server by default now, so there's a conflict when it tries to load it again via Nuget. The problem is, we obviously still need to reference the Nuget package in the project for our development machines to download it.
However, if this were the case, it seems like it would be a very common scenario but I found no other reports of this in the context of Azure Functions. So, I'm wondering if it's related to a recent change, or there's a unique situation afoot.
UPDATE:
Unfortunately, never understood or resolved the error or issue. The workaround was not reasonable, but I only had one big function app, so did it and it's over now. If you have many function apps with this error, I'm sorry.
The workaround was to follow the advice of #david-ebbo and effectively recreate my entire Function App. I also had to fully recreate all my shared class libraries including my test projects because of new compatibility issues. Overall, the new paradigm here is really looking good, and I attribute the excessive pain of this situation to working with multiple new and disruptive techs at the same time. Azure Functions + Visual studio + a .NET revolution. It took me about 3 hours to go and convert all my function.json files to method annotations, and move classes around, and then recreate the whole structure. It as very frustrating with a lot of trial and error, and I'm effectively still limited to only using .NET standard class libraries, which is an issue with a workaround for me.
#david-ebbo , please comment on my new issue if you don't mind.
Azure Function CI Build Error - Cannot create a file when that file already exists

Silverlight web service update fails to import wsdl

We've been battling with a strange issue for a couple of days now. Have searched the net for answers but none seem to solve the error.
Our scenario is: our organization has a Silverlight 5 application, which was developed in VS 2010, and everything was working fine. It is actually running in our production servers.Recently we migrated our development machines to VS 2015, and the machines themselves (new ones for the dept). The OS is Windows 7, same as before.
At first we were welcomed with that nasty MatchTimeoutInMilliseconds error, due to the MS Framework. Eventually MS released the 4.6.2 Preview version which covered this issue.
Ok. So back to implementing the changes requested, we created a new method in our webservice, and it complied just fine. We do have the [OperationContract] and [DataContract] tags in place. There is a question posted and answered with the justification that these tags were missing.However, when we go to the SL app and update the WS reference, we get this "Custom tool error: Failed to generate code for the service reference ..."
Custom Tool Warning messages include
"Cannot import wsdl:binding..."
"Cannot import wsdl:port..."
"Cannot import wsdl:portType..."
"No endpoints compatible with Silverlight 5 were found. The generated client class will not be usable unless endpoint information is provided via the constructor."
We're puzzled, because then we thought we might have done something wrong, so we rolled back the changes, and updated the service reference with no changes, and we get the same error. The Referece.cs file is generated with no code, and all references to the webservice are no longer recognized by the compiler.
We've also read some posts that offer as a solution unchecking "Reuse types in referenced assemblies". Doing that does clear these errors, only to generate others, since our app was built on this premise.
We've also tried deleting the service reference and adding it back again, but to no avail.
Eventually we reverted the SL app to the point it was compiling, which was before updating the webservice reference, republished the WS with the new method, and manually added the new method to the Reference.cs file, tested it and it works.
This, however, should not be -the- solution. It's a hassle and prone to errors.
We'd appreciate any help in solving this matter, or an insight as to why this is happening.
thanks

The whole problem is that, for some reason I still haven't found, VS fails to generate the code for Reference.cs.
As a workaround, we've managed to generate the Reference.cs file by using the SlSvcUtil.exe tool, located (on my machine) at "c:\Program Files (x86)\Microsoft SDKs\Silverlight\v5.0\Tools".
In order to get the same code as the one generated before the migration, I've used the following command and options:
SlSvcUtil.exe my_ws_address /namespace:"*,my_class_namespace" /ct:System.Collections.ObjectModel.ObservableCollection`1 /r:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\Silverlight\v5.0\System.Windows.dll" /edb /ser:Auto
I didn't use the /out switch, but rather ran the command on my desired output directory. But you might want to look into that switch before running the command.

How can I get started using OpenID/OAuth with my WebMatrix site?

If I misuse or confuse the terms OpenID and OAuth, I apologize, I am still new to this whole decentralized login process.
I have been trying for days now to get my site (built in WebMatrix) to recognize a Google login. The problem is I need this line of code (from what I've researched) in my _AppStart.cshtml file:
OAuthWebSecurity.RegisterGoogleClient();
But when I try to run this site after this statement is in place, I simply get a server error stating that OAuthWebSecurity.RegisterGoogleClient(); does not exist in the current context.
I thought I might need the OAuth library, a different helper, or some other package, but the only relevant package I see (Microsoft WebPages OAuth library 2.0.20710.0) I can't get, because WebMatrix doesn't support the version of NuGet it says that I need (2.0).
I have never used this method for a log in before and I want to learn how as I build this functionality for my clients. What I do not want to do is open up the starter template, and copy my files over. I have a problem using code that I don't understand. I feel that this would be a terrible habit for me to get into (it took some convincing myself before I would even use jQuery plug-ins). It also might bear mentioning that I will not be using any other third party service for this login. We use gmail for our employees' company email accounts so I need only Google logins for this solution.
Things I have tried:
Googling for other scenarios like mine. Fails because no relevant search results are found (i.e., I am unable to find results that match my scenario)
Searching for earlier versions of the Microsoft WebPages OAuth library 2.0.20710.0 package. Fails because my search returns no such packages.
Using OAuthWebSecurity.RegisterOpenIDClient(BuiltInOpenIDClient.Google); instead of OAuthWebSecurity.RegisterGoogleClient(); Fails for the same reason as when using OAuthWebSecurity.RegisterGoogleClient();
Visiting Site Administration and downloading the OAuth Library.
Fails because NuGet needs an update
Update Nuget Fails because of what is mentioned here (apparently, a known bug for WebMatrix): http://forums.asp.net/t/1836913.aspx/1?Error+updating+DotNetOpenAuth+updates+with+NuGet+Gallery
Opening up the Starter Site Template, which already has OAuth built in and functional.Fails to teach me as to why this site recognizes OAuthWebSecurity.RegisterGoogleClient() and mine doesn't, because there is no clear way (that I am aware of) to tell what pacakages, updates, and/or versions of third party software might be different.
Creating a new Starter Site and copying any OAuth based missing files from the *"App_Data"* and "bin" folders. Fails in that no behavioral changes were observed.
-----------------------------------------UPDATE----------------------------------------
So far, to date, the best solution for this problem, at least for me, has been to just use the "Starter Site" template in WebMatrix, whether I like it or not.
One of my biggest worries for doing this, however, was that there were so many extraneous files that I wasn't sure what I could and couldn't delete to keep the site clean while still leaving the OAuthWebSecurity() class fully accessible and functional. I have, however kept only the "bin" and "App_Data" folders (including all of their contents, of course) from the "Starter Site" template and deleted everything else (including the web.config file) before moving my files over, and this has appeared to work very well for me, so far.
Using the above mentioned steps, I have kept my site clean of unnecessary code, while still having access to the OAuthWebSecurity() class.
In the future (I imagine when WebMatrix 3 is released) this bug will probably be fixed and a simple admin site install of the OAuth library will not require a version of NuGet that WebMatrix does not support, but until then, this has been the best answer for me.

Does this GitHub project help : WorldDomination.Web.Authentication ??
there's also an MVC and NancyFX nuget package which does some auto wiring up, if that takes your fancy.
DISCLAIMER: I've never tried this in Webmatrix and will never plan on trying it, in that. That said, it might still work! :)

Have you tried following package?
PM> Install-Package Microsoft.AspNet.WebPages.OAuth

Install the Microsoft.AspNet.WebPages.OAuth package.
You can install it using the Package Manager Console, or in the GUI Package Manager.