How to Fix: WCF service startup error "This collection already contains an address with scheme http"
WCF service startup error due to duplicate http scheme address.
📋 Table of Contents
The WCF service startup error 'This collection already contains an address with scheme http' affects web applications that utilize Silverlight controls to make calls to a WCF service. This issue is frustrating because it prevents the application from functioning correctly, and resolving it requires careful analysis of the configuration and service setup.
Resolving this error involves identifying and addressing the conflicting configuration settings between the WCF service and its client applications. By following the steps outlined in this guide, you can successfully resolve the issue and get your web application up and running smoothly.
💡 Why You Are Getting This Error
- The primary reason for this error is that a single WCF service can have multiple addresses with different schemes (e.g., http, https, nettcp). When a client application, such as Silverlight, makes a call to the service using one scheme, and another address is already configured with the same scheme, it results in an exception. This occurs because the ServiceHost class uses a collection of addresses to route incoming requests.
- An alternative reason for this error could be due to incorrect configuration settings or missing endpoint mappings in the WCF service.
🛠️ Step-by-Step Verified Fixes
Renaming and Reconfiguring Addresses
- Step 1: Rename all existing addresses with scheme http to a unique identifier (e.g., 'http://localhost:8080/') to avoid conflicts.
- Step 2: Update the endpoint mappings in the WCF service configuration file (e.g., web.config or app.config) to use different schemes for each address. For example, you can use 'http' and 'https' separately for different endpoints.
- Step 3: Verify that all addresses are correctly configured and mapped to their respective endpoint types.
Alternative Fix Method: Using a Single Address with Multiple Schemes
- Step 1: Configure the WCF service to use a single address with multiple schemes (e.g., http://localhost:8080/). This approach allows you to reuse the same endpoint for multiple addresses, eliminating the need for renaming and reconfiguring.
- Step 2: Update the client application configuration to specify the correct scheme for each address. For example, if your service uses both 'http' and 'https', update your Silverlight control to use the correct scheme for each endpoint.
🎯 Final Words
By following these steps, you should be able to resolve the WCF service startup error 'This collection already contains an address with scheme http'. Remember to test your application thoroughly after resolving the issue to ensure that it functions correctly and meets all requirements.
❓ Frequently Asked Questions
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