# App does not open on some machines using C# DLL **URL:** \ **Category:** questions\ **Tags:** dll, dotnet\ **Created:** [March 9, 2023, 12:26pm UTC](https://clarionhub.com/t/app-does-not-open-on-some-machines-using-c-dll/6028 "2023-03-09T12:26:24Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Vinicius\_Souza](https://clarionhub.com/user_avatar/clarionhub.com/vinicius_souza/32/2394_2.png) [@Vinicius\_Souza](https://clarionhub.com/u/Vinicius_Souza)\ **Post date:** [March 9, 2023, 12:26pm UTC](https://clarionhub.com/t/app-does-not-open-on-some-machines-using-c-dll/6028/1 "2023-03-09T12:26:24Z")
Good morning, using this resource [https://clarionmag.jira.com/wiki/spaces/clarion/pages/400219/Clarion+and+C+.NET+Interop+without+COM?focusedCommentId=402206](https://clarionmag.jira.com/wiki/spaces/clarion/pages/400219/Clarion+and+C+.NET+Interop+without+COM?focusedCommentId=402206), I was able to create DLLs made in C# to use in Clarion. Tests Ok, production Ok, but on some machines the Clarion APP simply does not open. It seems that the dlls are linking and an error occurs that is not shown. Scenario is the C# DLL, which just does an internet connection test. This C# DLL is called by a Clarion DLL and this Clarion DLL is linked with a normal Clarion App. I'm trying to map where is the possible problem that may be breaking. But it's hard to know if the problem is in the linking of the DLLs or if it's a Windows issue. ---
**Author:** ![ThalesSilveirs](https://clarionhub.com/user_avatar/clarionhub.com/thalessilveirs/32/3642_2.png) [@ThalesSilveirs](https://clarionhub.com/u/ThalesSilveirs)\ **Post date:** [March 9, 2023, 1:22pm UTC](https://clarionhub.com/t/app-does-not-open-on-some-machines-using-c-dll/6028/2 "2023-03-09T13:22:19Z")
Have you tested whether you have installed the C# Runtimes? Couldn’t that be it? > **[Browse all .NET versions to download | .NET](https://dotnet.microsoft.com/en-us/download/dotnet)** > > Official .NET downloads for Linux, macOS, and Windows. .NET is a free, cross-platform, open-source developer platform for building many different types of applications. ---
**Author:** ![Vinicius\_Souza](https://clarionhub.com/user_avatar/clarionhub.com/vinicius_souza/32/2394_2.png) [@Vinicius\_Souza](https://clarionhub.com/u/Vinicius_Souza)\ **Post date:** [March 9, 2023, 1:51pm UTC](https://clarionhub.com/t/app-does-not-open-on-some-machines-using-c-dll/6028/3 "2023-03-09T13:51:09Z")
I didn’t do that check. I’ll see it now. ![erroDllSoma1](https://clarionhub-uploads.s3.eu-north-1.amazonaws.com/original/2X/b/b2393529ef56d1ba35419c67d42676a1012ad267.png) ![erroDllSoma2](https://clarionhub-uploads.s3.eu-north-1.amazonaws.com/original/2X/3/3c41d284b7943ad22ca2df7722a27d7c8d84bbed.png) Before that, I went through the windows error logs, found this, but haven’t done a detailed analysis yet ---
**Author:** ![Vinicius\_Souza](https://clarionhub.com/user_avatar/clarionhub.com/vinicius_souza/32/2394_2.png) [@Vinicius\_Souza](https://clarionhub.com/u/Vinicius_Souza)\ **Post date:** [March 9, 2023, 2:02pm UTC](https://clarionhub.com/t/app-does-not-open-on-some-machines-using-c-dll/6028/4 "2023-03-09T14:02:48Z")
Yes, C# Runtimes installed. On the machine that is experiencing this problem, I run other applications that are .NET. Doing other tests, the Clarion APP calling directly the DLL made in C# works OK. But APP Clarion, calling a Clarion DLL, and that Clarion DLL calling the C# DLL that causes the problem. Confusing yes, I know.. ---
**Author:** ![Mike\_Duglas](https://clarionhub.com/user_avatar/clarionhub.com/mike_duglas/32/1061_2.png) [@Mike\_Duglas](https://clarionhub.com/u/Mike_Duglas)\ **Post date:** [March 9, 2023, 2:13pm UTC](https://clarionhub.com/t/app-does-not-open-on-some-machines-using-c-dll/6028/5 "2023-03-09T14:13:12Z")
Put OutputDebugString calls before / after critical points like calling external functions, internet connection attempt and so on.