After upgrading my project to ASP.NET Core 2.2, I tried to run the application (locally of course) and the browser displayed an error message like in the below screenshot.
no more errors notified by visual studio error explorer. I don't know what's happen.
I ran into this issue and had a different solution. For me it was that I had a package that was out of date with the application (I had updated it on NuGet, and the library hadn't been replaced in production). Updating the package fixed it for me.
Note with this: I had to manually run dotnet.exe with the project dll in order to see the message that fixed it for me.
Hope this helps someone else down the road.
you have 2 solution(this answer works on windows server I do not know anything about linux server).
first:
copy all folder(except bin and obj folder) of your project to server
open cmd in your project folder then run this command: dotnet run then all warning and error show to you(if you have error about above command not recognize download dot net core sdk from this link)
second:
in my case web.config is:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<location path="." inheritInChildApplications="false">
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath="dotnet" arguments=".\BMS.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="OutOfProcess" />
</system.webServer>
</location>
</configuration>
and I change it to:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<location path="." inheritInChildApplications="false">
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath="dotnet" arguments=".\BMS.dll" stdoutLogEnabled="true" stdoutLogFile=".\logs\stdout" hostingModel="inprocess" />
</system.webServer>
</location>
</configuration>
I encountered this error after trying to publish from VS2017 to the production Windows 2016 server. (It worked fine in IIS Express on my local Win10 PC.)
I updated packages, all versions matching and updated in my code, .net core versions matching, restart IIS, rebooting... no joy.
In the Publish > Configure > Settings (left tab) I had to set the Target-runtime from "Portable" to "win-x64" (or whatever is relevant to your environment). I also opted to "Remove additional files at destination."
"Portable" is the default setting. I'm not sure what it takes for the "Portable" runtime to work properly, but might save someone else some time if a "Portable" runtime is not something you need.
Generally speaking, I get this error if something is mismatched in my environment. For example, one time I was upgrading one of my projects to .Net Core 3.1 from 2.2 and hadn't installed the ASP.NET Core Runtime Hosting Bundle on my server:
https://dotnet.microsoft.com/download/dotnet-core/3.1
Also, you can get this error if your Application Pool is set to True for Enable 32-Bit Applications. Try:
IIS Manager > Application Pools > app pool name > (right click) Advanced Settings > Enable 32-Bit Applications = False
Seems that everyone has a different answer for this. I also had this issue as well. There are many different things as you can tell that cause this issue. If you don't find any of these solutions helpful or have issues trying to go through all these different solutions, you can try running your application from the command line from the publish folder.
After publish, if you receive this error, go to your publish folder, and then open a command/terminal window, after that type dotnet .\YourStartupProject.dll, you should receive an exception error, which should make fixing the issue easier.
For example, this is an error I received on trying on a new environment without setting up a SQL server, and of course, would receive this error.
Application startup exception: System.Exception: Could not resolve a service of type
'YourStartupProject.DataServices.DbContext.DbContext' for the parameter
'context' of method 'Configure' on type 'YourStartupProject.Startup'. --->
System.ArgumentNullException: Value cannot be null.
Parameter name: connectionString
Once you resolve your error, try it again, rinse, repeat.
I ran into this issue today with my hosting - locally everything is ok but once I publish, I get this error.
I looked through the packages and found out that some .net core stuff was upgraded to 3.0 preview.
Then I changed the build option in VS2019 from "Framework-Dependent" to "Self-contained". It took 5 times longer to build and publish but now it works.
Now I'm checking with host tech support what might be an issue - officially they support 2.1 / 2.2 only, so this might be these packages from 3.0 Preview, however target build is 2.2.
If resetting the project and manually copying Program and Startup classes worked for you, then something was clearly messed up. There are some bigger underlying problems with this. Using the OutOfProcess hosting model is okay, but with .Net Core 2.2 you should be able to use the InProcess hosting model, since it is naturally faster: everything is processed in IIS, without an extra HTTP-hop between IIS and your app's Kestrel server.
If you right-click your project file in the visual studio solution explorer, please make sure that AspNetCoreModuleName tag has AspNetCoreModuleV2 value (as opposed to the older AspNetCoreModule). Also, examine Windows Application Event Log to identify the potential culprit. Even though error messages there are somewhat cryptic, they might point you to the exact line number in the code that caused the failure.
Finally, in case you use CI/CD with TFS, there may be environment variable(s) in appsettings.json file that were not properly replaced with the actual values (URLs, etc.).
Looks like i had the same issue. It's happens because if you don't have global.json file in solution, then VS build(publish) .net core app with the last version that installed on your pc. So, i do the next solution:
add a global.json file with .net core version.
{
"sdk": {
"version": "2.2.402"
}
}
From docs.microsoft.com:
global.json can be placed anywhere in the file hierarchy. The CLI searches upward from the project directory for the first global.json it finds. You control which projects a given global.json applies to by its place in the file system. The .NET CLI searches for a global.json file iteratively navigating the path upward from the current working directory. The first global.json file found specifies the version used. If that version is installed, that version is used. If the SDK specified in the global.json is not found, the .NET CLI rolls forward to the latest SDK installed. Roll-forward is the same as the default behavior, when no global.json file is found.
https://docs.microsoft.com/en-us/dotnet/core/versions/selection
For me the issue was caused by dotnet publish creating a web.config entry stdoutLogFile=".\logs\stdout". The correct value should be stdoutLogFile="\\?\%home%\LogFiles\stdout".
MSDN reference: https://blogs.msdn.microsoft.com/waws/2018/06/10/troubleshooting-http-502-5-startup-issues-in-azure-appservice-for-asp-net-core-websites/
This could be a bug in the ASP.NET Core 2.2.0 runtime which may have been fixed in a later version.
This happened to me first time publishing an Azure Web App. Here is how I solved it:
Browse the site using Kudo/FTP. In the root folder there is a LogFiles folder where you find eventlog.xml. In this file I could see that my web app had an SqlException when Entity Framework Core was trying to setup the database, which lead me to check the database permissions (which was the problem for me).
Follow this steps:
create a directory in root of your project : logs/stdout
open the web.config file from root of your project and find this line:
<aspNetCore processPath=".\web.exe" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
set stdoutLogEnabled as true and save it
reload your app and see the logs in the directory : logs/stdout
This error started appearing on our Dev server. I had been using this publish command which creates a "self-contained" folder of files for deployment.
dotnet publish -c release -r win7-x64 --output:bin/self_contained
My fix was to instead publish a "framework-dependent" deployment using the following command:
dotnet publish --output:bin/framework_dependent
The dev server did have a few versions of .NET Core installed (2.2.3 and 2.2.5) in this folder *C:\Program Files\dotnet\shared
I am still not clear on why the self contained publish does not work. You might think the self contained publish would be the more reliable method, but in my case it was not.
This .NET Core blog post was helpful.
The problem occurs when I try to deploy the asp.net core (out-of-process hosting model) website to windows server 2012r2 IIS in production env. I fixed this with this solution:
I was also getting the same issue. And when I looked at the Output window of my solution.
Then I was able to see a different error, which is "The target process exited without raising CoreCLR started event", to fix this I had to remove the Microsoft.AspNetCore.All from my Nuget Packages and install Microsoft.AspNetCore.App. I also had to install the correct .Net SDK from here. Once this is done, restarted my machine and open the solution, the error was gone. Hope it helps
In my case EF Migrations thrown exception about blocking executing one of them because of a potential data loss. I had to look into custom app logs (most often Log folder) to find out that.
I guess the Error mentioned in the Question is due to problems during app start stage. And indeed the migrations are run during starting an app, so if they fail the app is not able to complete starting.
So in general when we get such Error we should focus on things that impact on starting logic of the app.
For me it was the web.config file, make sure you have it and to specify the paths correctly
<aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" stdoutLogEnabled="false" stdoutLogFile=".\bin\Debug\netcoreapp2.0\logs\stdout">
Also the event viewer can be useful to detect app startup errors.
