Skip to main content

Resolving error 'The underlying connection was closed: An unexpected error occurred on a send' in NAVISION / Business Central


Today, as I was working with Real-Time Integration with TCI Scribe, I noticed that the integrations which were working prior stopped working.
Although the URL when triggered through the POSTMAN app it works fine.
The error that was received is '{​​​​​"The underlying connection was closed: An unexpected error occurred on a send."}​​​​​'


  • Microsoft Dynamics NAV / Business Central
  • Understanding of .NET Interoperability
  • Postman App
  • Test Endpoint for API


I have used NAVWebRequest or HTTPWebRequest as .NET interoperability in NAV referring to
1. Debugging the issue:
In order to make sure that the coding is correctly triggering the URL with POST call and JSON Data Payload, I created an endpoint on Request Bin and the solution seems to be working.
Request Bin

Also, when triggering the URL through Postman, the response is correctly generated.
Postman Trigger

2. Finding the issue and possible solution using C#:
We created a code in C# to test if this could be done through C# Console Application and still got the error.

The connection is force closed.

After setting the Security Protocol in C# code prior to calling HTTP Request the issue gets resolved.
Request processed successfully

3. NAV equivalent code:
Variable declaration:

ServicePointManager DotNet System.Net.ServicePointManager.'System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089'
SecurityProtocolType DotNet System.Net.SecurityProtocolType.'System, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089'

Adding Service Point Manager Security Protocol

4. Output:
Finally, the integration started working successfully by triggering the URL from NAV.


The cause of this issue was that there are security enhancements in API Endpoints and it requires TLS Security Protocol to be set prior to triggering the request.

Special thanks to Subash Mahato for helping me with the C# code to confirm the issue and find its resolution.


Popular posts from this blog

Something went wrong. An Error occurred - Error Resolution

Introduction: With the installation of NAV 2018 or BC On-premise, I have observed that when creating New Server Instance and New WebServer Instance, you will get the error 'Something went wrong. An Error occurred '. I referred to the community questions below but didn't find my resolution. Hence, I decided to write this blog. Pre-requisites: Microsoft Dynamics Business Central - On-Premise / NAV 2018 Understanding of Business Central Authentication  Books & References: Demonstration: 1. Creation of NAVServerInstance: In order to create NAVServerInstance, you can either add the Server Instance through Business Central Administration or Powershell command. Add Instance - Business Central Administration Add Insta

Universal Code Error and Resolution

Introduction: On Friday, May 12th, 2023, the Business Central On-Premise Production Environments started throwing universal code errors as follows. This occurred to every customer on a lower version of BC 19,20 and 21 irrespective of their localization, customization, and license. Pre-requisites:  Understanding of Technical Upgrade in Business Central On-Prem References: BC20 On prem. Universal Code requirement error after installing customer's license. - Dynamics 365 Business Central Forum Community Forum (40) Yammer : Dynamics 365 Business Central Development : View Conversation Root Cause: The certificate that signs Microsoft Base Application was expired. Errors started occurring if you Uninstalled, Installed Extensions, Restart Server Instances or for some even out of random started popping out. We first thought could be a license issue as we had fixed that before but this did not solve the issue. Resolution: Microsoft identified the issue and posted the following update The mi

How to update your Business Central to Latest CU

Introduction:  There are times when Microsoft releases the latest major version upgrade for Business Central Upgrade and you face many issues with it. As soon as the bugs are reported to Microsoft, they start to fix them and ask you to upgrade to a certain Cumulative Update. In this blog, I will be sharing my experience with Business Central v21 CU0 upgrade to Business Central v21 CU2. Pre-requisites:  Business Central DVD for Latest CU Basic Understanding of Business Central CU Updates Books & References:  List of Update Packages How to Update CU version Demonstration:  1. Check the current state of BC: As part of knowing the current state of your Business Central environment, I'm assuming that your Business Central Environment will have some data in the standard Base App also there will be customization with extended tables and newly created tables. Customization - TableExtension on Customer Table  Customization - Custom Table created Make a note of the data that is present i