Invalid web.config causes HTTP 502.5 error - asp.net

Question

I am trying to deploy an Asp.net boilerplate app on azure and I have already deployed my backend and the Swagger application is working fine, when I try to also deploy the Angular frontend I keep getting this error: HTTP Error 502.5 - ANCM Out-Of-Process Startup Failure.
I have found other threads discussing this problem, but since I am using the ASP.NET Boilerplate framework i do not have a .exe or .dll file that I can run to start the Web.Host project, not that I'm aware of atleast.
The logs in Kudu show this: Application '/LM/W3SVC/288745522/ROOT' with physical root 'D:\home\site\wwwroot\' failed to start process with commandline '%LAUNCHER_PATH% %LAUNCHER_ARGS%'.
It probably has something to do with those %LAUNCHER% variables not being found, I have found some other threads suggesting your should replace the LAUNCHER_ROOT [projectname].exe or [projectname].dll but I cant seem to find these in my project. This might be because of the way ASP.NET Boilerplate is built up.
This is my web.config:
<configuration>
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" stdoutLogEnabled="true" stdoutLogFile=".\logs\stdout" forwardWindowsAuthToken="false" startupTimeLimit="3600" requestTimeout="23:00:00">
<environmentVariables />
</aspNetCore>
<httpProtocol>
<customHeaders>
<remove name="X-Powered-By" />
</customHeaders>
</httpProtocol>
</system.webServer>
</configuration>

Answer 1

Error message indicates that the ASP.NET Core Module attempts to start the worker process but it fails to start. The cause of a process startup failure can usually be reviewed from entries in the Application Event Log and the ASP.NET Core Module stdout log. Both logs can be found on the Kudu/SCM site in d:\home\Logfiles. In your web.config file located in the wwwroot folder, enable stdout logs, as so:
Web.config sample:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath="dotnet" arguments=".\MyApplicationAssembly.dll" stdoutLogEnabled="true"
stdoutLogFile="\\?\%home%\LogFiles\stdout" forwardWindowsAuthToken="false" />
</system.webServer>
</configuration>
Please check the eventlog.xml and the stdout logs you have collected.
Reference: https://blogs.msdn.microsoft.com/waws/2018/06/10/troubleshooting-http-502-5-startup-issues-in-azure-appservice-for-asp-net-core-websites/
Additional troubleshooting methods for ASP.Net at
https://learn.microsoft.com/en-us/aspnet/core/test/troubleshoot-azure-iis?view=aspnetcore-2.2#troubleshoot-on-azure-app-service.
Hope it helps.