C# NFC-Project with PCSC Library – An error has occurred: An attempt was made to end a non-existent transaction

If you’re working on a C# NFC project using the PCSC library, you may have encountered the frustrating error “An attempt was made to end a non-existent transaction.” This error can occur due to various reasons, and in this article, we’ll dive into the possible causes and provide step-by-step solutions to help you resolve the issue.

What is PCSC Library?

The PCSC library is an open-source implementation of the PC/SC (Personal Computer/Smart Card) standard, which allows developers to create applications that interact with smart cards and other devices. In the context of an NFC project, the PCSC library is often used to communicate with NFC readers and tags.

The Error: An attempt was made to end a non-existent transaction

This error typically occurs when your application tries to close or end a transaction that hasn’t been started or doesn’t exist. This can happen due to various reasons, such as:

• Incorrect initialization of the PCSC library
• Failure to start a transaction before performing operations
• Using an invalid or closed connection to the NFC reader
• Not releasing resources properly after completing a transaction

Solution 1: Verify PCSC Library Initialization

Ensure that you’ve correctly initialized the PCSC library by following these steps:

1. Install the PCSC library NuGet package in your C# project
2. Import the PCSC library namespace: using PCSC;
3. Initialize the PCSC library using the following code:

   var ctx = new SCardContext();
   ctx.Establish(SCardScope.System);
   

Solution 2: Start a Transaction Before Performing Operations

Make sure you start a transaction before performing any operations on the NFC reader. You can do this by using the SCardBeginTransaction method:

var readerName = "Your_NFC_Reader_Name";
var hCard = ctx.Connect(readerName, SCardShareMode.Shared, SCardProtocol.Any);
hCard.BeginTransaction(SCardIsoProtocol.Any);

Solution 3: Verify the Connection to the NFC Reader

Ensure that you have a valid connection to the NFC reader before performing operations. You can check the connection status using the SCardStatus method:

var status = hCard.Status();
if (status.Succeeded)
{
    Console.WriteLine("Connected to NFC reader successfully");
}
else
{
    Console.WriteLine("Failed to connect to NFC reader");
}

Solution 4: Release Resources After Completing a Transaction

After completing a transaction, make sure to release the resources properly to avoid conflicts. You can do this by using the SCardEndTransaction and SCardDisconnect methods:

hCard.EndTransaction(SCardDispose.ReturnValue);
hCard.Disconnect(SCardDispose.ReturnValue);

Additional Tips and Considerations

When working with the PCSC library and NFC readers, keep the following tips and considerations in mind:

Tips and Considerations	Description
Use the correct NFC reader name	Make sure to use the correct name of your NFC reader when connecting to it.
Handle exceptions properly	Always handle exceptions and errors properly to avoid application crashes and unexpected behavior.
Use the correct transaction mode	Use the correct transaction mode (e.g., SCARD_SHARE_SHARED or SCARD_SHARE_EXCLUSIVE) depending on your application’s requirements.
Release resources in finally blocks	Always release resources in finally blocks to ensure they’re released even in case of exceptions.

Conclusion

The “An attempt was made to end a non-existent transaction” error can be frustrating, but by following the solutions and tips outlined in this article, you should be able to resolve the issue and continue developing your C# NFC project with the PCSC library. Remember to initialize the PCSC library correctly, start a transaction before performing operations, verify the connection to the NFC reader, and release resources properly after completing a transaction.

If you’re still experiencing issues or have further questions, feel free to ask in the comments section below. Happy coding!

Frequently Asked Question

Get answers to the most common issues when working with C# NFC-Project using PCSC Library. If you’re stuck, we’ve got you covered!