Software⏱️ 3 min read📅 2026-06-19

How to Fix: Error when trying to start a device in GNS3?

GNS3 error when starting IOS device, DynamipsError and unable to create VM instance.

Quick Answer: Check the image file for corruption or invalid parameters. Try using a different image file or updating GNS3.

📋 Table of Contents

  1. 🛑 Root Causes of the Error
  2. 🔧 Proven Troubleshooting Steps
  3. ✨ Wrapping Up

Error when trying to start a device in GNS3 occurs when the user attempts to boot up a virtual router or switch using the c2691 IOS image provided by GNS3. This issue affects users of both Windows 7 and Ubuntu 13.04 operating systems, causing frustration as it prevents the user from successfully starting the device.

Resolving this error is crucial as it hinders the ability to perform simulations and experiments with virtual devices in GNS3.

🛑 Root Causes of the Error

  • The primary reason for this error lies in the Dynamips library's inability to properly handle the c2691 IOS image. The image may be corrupted or have an incorrect configuration, leading to a Bad number of parameters (3) error when attempting to start the device.
  • Another possible cause is related to the VM instance creation process. It's possible that the ghost file for the c2691 IOS image is not being created correctly, resulting in an unable to create VM instance error.

🔧 Proven Troubleshooting Steps

Method 1: Verifying Image Integrity

  1. Step 1: Download the c2691 IOS image from a trusted source or official GNS3 website.
  2. Step 2: Verify the integrity of the downloaded image by checking its MD5 hash using tools like md5sum or checksum.
  3. Step 3: Compare the calculated MD5 hash with the provided one in the GNS3 image to ensure they match. If not, contact GNS3 support for assistance.

Method 2: Checking VM Instance Creation

  1. Step 1: Check the Dynamips library logs for any errors related to VM instance creation.
  2. Step 2: Verify that the ghost file is being created correctly by checking its contents and permissions. Ensure that the file has the correct ownership and access rights.
  3. Step 3: Try creating a new VM instance with the c2691 IOS image using a different method, such as using the 'create_vm' command in the GNS3 console.

✨ Wrapping Up

To resolve the Error when trying to start a device in GNS3, follow one of the methods outlined above. If you're still experiencing issues after attempting these steps, contact GNS3 support for further assistance or consider reaching out to the GNS3 community forums for help from other users.

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