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Unable to determine if a file is on a web server because the various methods of determining the directory do not work

I am developing an application in asp.net, vs2015 using c# and the development environment is a Win10Pro machine. I can use any of the various methods to obtain the working directory and see if a particular file exists on the dev pc, but not on the Web Server. I have tried the methods laid out on:
Get current application physical path within Application_Start
All work on the Dev PC, but when used on the Web Server it will not return the working directory. The Server is a 2016 Data server using IIS10. The issue is that the web site I am putting together work fine, except to display GrapeCity ActiveReports reports AR15. The web page containing their web viewer opens just fine and is looking for a report file (MyReport.rdlx). The global.aspx file is pointing to the root directory but when the web viewer opens up, it says File Not Found. I have absolutely no idea and tech support is not sure. Is this an IIS issue that is preventing the code to locate and verify the file is there? Any direction would be much appreciated. This has been very frustrating and time consuming.
AppDomain.CurrentDomain.BaseDirectory does not work, HttpRuntime.AppDomainAppPath does not as well as all the others. The request comes back blank.
string filename = AppDomain.CurrentDomain.BaseDirectory.ToString() +"SPU01_Dates.rdlx";
if (File.Exists(filename))
{
Response.Write("YES");
}
else
{
Response.Write("NO");
Response.Write("</br");
Response.Write(filename);
}
All this just returns nothing.
Thanks.

Try this code
if (File.Exists(Server.MapPath(filename)))
Check if a file exists on the server

In my test, it returned YES and worked well. Did you put "SPU01_Dates.rdlx" file in root folder？
In the development environment, it returned YES, and when I deployed it to IIS, it returned NO. I found that during the deployment process, the rdlx file was not deployed with the project, so I recreated one in the deployed folder, and it returned YES.
The test proves that AppDomain.CurrentDomain.BaseDirectory is the most accurate way to get the file path. When you test this code in IIS, does it return NO or empty? Returning empty means that this piece of code has not been executed.

Application can find 'Downloads' folder when debugging but not on IIS

I have an application that allows the user to upload a file (saving it to in a folder located in the wwwroot of the ASPNETCORE application). From here they can make edits to it and then they can choose to export the file as a csv/ xml/ xlsx which downloads the file to the user's 'downloads' folder.
While debugging in Visual Studio this all works fine however when I publish and deploy the application to IIS I am getting the exception
Error saving file C:\windows\system32\config\systemprofile\Downloads(FILE NAME)
Could not find part of the path C:\windows\system32\config\systemprofile\Downloads(FILE NAME)
This is the current way I am getting the downloads folder:
FileInfo file = new FileInfo(Path.Combine(Environment.ExpandEnvironmentVariables(#"%USERPROFILE%\Downloads"), data.Filename + "." + data.FileType));
However I have also tried the solution that Hans Passant has answered to a similar question here. Both solutions worjk fine while debugging locally however as soon as I publish them, this one produces the exception:
Value cannot be null. Parameter name: path1
Which I presume is thrown at this point here when I try and save the file to the user's download folder.
using (var package = new ExcelPackage(file))
{
var workSheet = package.Workbook.Worksheets.Add("ExportSheet");
workSheet.Cells.LoadFromCollection(exports, true);
package.Save();
}
I don't really know how I would be able to reproduce these exceptions seeing as locally using Visual Studio it all works fine.
Has anyone else came across this issue while trying to download a file?
UPDATE: When the application is running on IIS, it seems to be using that as the user profile instead of the actually user, so when it tries to navigate to the Downloads folder, it cannot find it. How can I force it to use the user's profile?
LoadUserProfile is already set to True.

Web applications have no knowledge of the end-user's computer's filesystem!
So using Environment.GetFolderPath or Environment.ExpandEnvironmentVariables in server side code will only reveal the server-side user (i.e. the Windows Service Identity)'s profile directories which is completely separate and distinct from your web-application's actual browser-based users OS user profile.
As a simple thought-experiment: consider a user running a weird alien web-browser on an even more alien operating system (say, iBrowse for the Amiga!) - the concept of a Windows-shell "Downloads" directory just doesn't exist, and yet here they are, browsing your website. What do you expect your code would do in this situation?
To "download" a file to a user, your server-side web-application should serve the raw bytes of the generated file (e.g. using HttpResponse.TransmitFile) with the Content-Disposition: header to provide a hint to the user's browser that they should save the file rather than try to open it in the browser.

Printing Telerik reports using ReportProcessor class

Firstly let me describe my setup.
I have a REST Telerik Reporting service. The service operates with TRDX file (have a requirement to have reports in this template format). I also have a console application, which is periodically started by a windows service. This console application uses ReportProcessor class to print reports directly to a printer.
Now the problem.
ReportProcessor throws an exception when trying to access the reports using UriReportSource, when these report files are hosted in IIS together with the REST Reporting service. Browsing and Anonymous Authentication are enabled on IIS for the Reports folder. The error that's thrown is:
The remote server returned an error: (404) not found.
However reports are printed when TRDX files are located in the same folder as the console application.

Solved my own question by trial and error.
My reports were located in the REST service's subdirectory. So I was trying to set the Uri to the reports URL something like this:
UriReportSource reportSource = new UriReportSource {
Uri = "http://localhost/myTelerikRESTService/Reports/samplereport.trdx"
};
And I was obviously getting 404 error since the request to the that path would be handled by the service.
Trying to specify a physical path (c:\inetpub\wwwroot\myTelerikService\Reports\samplereport.trdx) also ended up in error: something like the path format is not supported.
Finally I've tried this Uri: /inetpub/wwwroot/myTelerikService/Reports/samplereport.trdx, that maps to the physical location.
And it worked!
EDIT:
I really should've read this https://www.w3.org/Addressing/URL/uri-spec.html before working on this issue. Apparently I had no firm understanding of what a URI is! Feeling really dumb now.....

My C# application is returning 0xE0434352 to Windows Task Scheduler but it is not crashing

I have written a few C# apps that I have running via windows task scheduler. They are running successfully (as I can see from the log files that they are writing ) but windows task scheduler shows them returning a last run result of 0xE0434352. Is there something I need to do in my C# application so that it returns a success code to the windows task scheduler?

Another option is to simply use the Application log accessible via the Windows Event Viewer. The .Net error will be recorded to the Application log.
You can see these events here:
Event Viewer (Local) > Windows Logs > Application

When setup a job in new windows you have two fields "program/script" and "Start in(Optional)". Put program name in first and program location in second.
If you will not do that and your program start not in directory with exe, it will not find files that are located in it.

Hans Passant was correct, I added a handler for AppDomain.CurrentDomain.UnhandledException as described here http://msdn.microsoft.com/en-us/library/system.appdomain.unhandledexception(v=vs.71).aspx I was able to find the exception that was occurring and corrected it.

I was referencing a mapped drive and I found that the mapped drives are not always available to the user account that is running the scheduled task so I used \\IPADDRESS instead of MAPDRIVELETTER: and I am up and running.

In case it helps others, I got this error when the service the task was running at didn't have write permission to the executable location. It was attempting to write a log file there.

I had this issue and it was due to the .Net framework version. I had upgraded the build to framework 4.0 but this seemed to affect some comms dlls the application was using. I rolled back to framework 3.5 and it worked fine.

I got the same error but I have fixed it by changing the file reading path from "ConfigFile.xml" to AppDomain.CurrentDomain.BaseDirectory.ToString() + "ConfigFile.xml"
In my case, this error due to file path error because task manager starts program from "System32" as initial path but the folder we thought.

I was getting the same message message within dotNet Core 2.2 using MVC 5, however nothing was being logged to the Windows Event Viewer.
I found that I had changed the Project sdk from Microsoft.NET.Sdk.Web to Microsoft.NET.Sdk.Razor (seen within the projects.csproj file). I changed this back and it worked fine :)

In my case it was because I had message boxes. Once I commented that code out, it started working. I remembered that could be a problem when I looked at the event log as suggested in this thread. Thank you everyone!

I encountered this problem when working with COM objects. Under certain circumstances (my fault), I destroyed an external .EXE process, in a parallel thread, a variable tried to access the com interface app.method and a COM-level crash occurred. Task Scheduler noticed this and shut down the app. But if you run the app in the console and don't handle the exception, the app will continue to work ...
Please note that if you use unmanaged code or external objects (AD, Socket, COM ...), you need to monitor them!

Also message box in PowerShell. I converted PowerShell script to exe. When running as admin it's worked but in task schedule I received this error also.
There was an line in PowerShell script with write-output. After commented this line and compile new exe Task Schedule was completed successfully.

It is permission issue in my case the task scheduler has a user which doesn't have permission on the server in which the database is present.

Mathematica .Net/Link in an Asp.Net application

I am using the Mathematica .Net/Link platform to create a web service to format and calculate math problems. However I am unable to get it working.
I create it using this code:
_Log.IpDebug("Starting the Kernel Link");
if (string.IsNullOrEmpty(_MathLinkArguments))
_InternelKernel = MathLinkFactory.CreateKernelLink();
else
_InternelKernel = MathLinkFactory.CreateKernelLink(_MathLinkArguments);
_Log.IpDebug("Kernel Link Started");
_InternelKernel.WaitAndDiscardAnswer();
The value of _MathLinkArguments is -linkmode launch -linkname \"C:\\Program Files\\Wolfram Research\\Mathematica\\7.0\\Math.exe\".
This piece of code is called from the Application_Start method of the global.asax.cs file.
When it gets to the WaitAndDiscardAnswer() call it gives the server error:
Error code: 11. Connected MathLink program has closed the link, but there might still be data underway.
Note: The SampleCode given with the .NET/Link package (both a console app and a WinForms app) works.
Edit:
I copied the console app sample code given with Mathematica into an asp.net page and it gave me the same error the first load and then on subsequent loads it gave me:
Error code: 1. MathLink connection was lost.
Edit2:
I forgot to mention that when I have procmon and task manager open while running my app, I can tell that Math.exe starts but it immediately exits, which makes those error code make complete sense...but doesn't explain why that happened.

To allow the .Net/Link to work in Asp.net (at least in IIS 7.5) you need to enable the property loadUserProfile on the app pool for the web site.
I am not entirely sure why this is the case, but from what I found while trying to debug this, there are some things that are gotten from the user's profile. I know for a fact that the default location of the kernel is, which explains why I couldn't use it with no arguments, and so I can only assume that other things are needed as well and without the profile it couldn't determine that.
But whatever the reason is this is required, it is, or at least it is a fix if you are getting similar problems like this in your own application.

I got the same error in a .Net WinForm application.
mathKernel = new MathKernel();
mathKernel.Compute("<< XYZ`XYZGraphs`");
The error occurred on loading the package straight after instantiating the MathKernel.
To resolve it you can wait a couple of seconds and then instantiating the MathKernel works fine. During this state where there might still be data underway the following conditions are both false:
if (!MathKernel.IsConnected)
{
MathKernel.Connect();
}
if (MathKernel.IsComputing)
{
MathKernel.Abort();
}
Edit:
I've recieved the error again and this time was able to determine the problem.
Using a command line open the MathKernel.exe and view the error message: