Services
Technology Web App Development Mobile App Development Windows App Development Database Development UI/UX Development Cloud Development SEO Digital Marketing Guest Posting Content Writing Artificial Intelligence Data Science ERP Development CRM Development CMS Development LMS Development Business Listing Blockchain Technology Startup Promotion
Products
Data Converter Cleaner TUC - Unit Converter Import Export Survey Manager Tweet Controller
Developer
Article Blog Forum Interview Beginner News Startup Quiz
Users
Career
Apply Job Internship
Pricing
Login Sign Up Get a Quote

forum

home / developersection / forums / what is the difference between throw and throw ex?
Ask Question

What is the difference between throw and throw ex?

Anubhav Sharma 505 19 Jun 2025

What is the difference between throw and throw ex?

c# c#
Updated 23 Jun 2025
Anubhav Sharma
Anubhav Sharma

Student

The Anubhav portal was launched in March 2015 at the behest of the Hon'ble Prime Minister for retiring government officials to leave a record of their experiences while in Govt service .

Message

1 Answers

Ponu Maurya
Ponu Maurya 23 Jun 2025
Report Abuse

In C#, throw and throw ex both raise exceptions, but they behave differently when it comes to preserving the original stack trace.

throw vs throw ex – Core Difference

Keyword Stack Trace Preserved? Use Case
throw Yes Rethrow original exception
throw ex No Replaces stack trace (avoid unless modifying)

1. throw – Rethrows the original exception

When you use throw alone inside a catch block, it rethrows the original exception without losing the stack trace.

try
{
    // Some code that throws
}
catch (Exception ex)
{
    // Do logging, then rethrow
    LogError(ex);
    throw; // ✅ Preserves original call stack
}
  • Keeps the exact line where the error occurred.
  • Preferred for logging and rethrowing.

2. throw ex – Resets the stack trace

When you use throw ex, you create a new exception context, which resets the stack trace to the current line. This makes debugging harder.

try
{
    // Some code that throws
}
catch (Exception ex)
{
    // ❌ Replaces original stack trace
    throw ex;
}
  • Looks like the error occurred in the catch block.
  • You lose information about where the exception was originally thrown.

Example:

void Divide()
{
    try
    {
        int x = 0;
        int y = 10 / x; // Error: DivideByZeroException
    }
    catch (Exception ex)
    {
        throw;    // ✅ stack trace points here: int y = 10 / x
        // throw ex; // ❌ stack trace points here: throw ex
    }
}

Best Practice:

Always prefer throw when rethrowing an exception to preserve debugging details.

Use throw ex; only if:

  • You’re modifying the exception (e.g., wrapping it in another exception type).
  • You’re deliberately restarting the stack trace for design reasons.

Wrapping Example (valid use of throw ex):

catch (Exception ex)
{
    throw new CustomAppException("Something failed.", ex);
}
MindStick Training