How to fix Error Getting Design Time Data in Blend with MVVM-Light

By
Caleb Jenkins
– June 10, 2012Posted in: Featured, Technology

I ran in to this recently and couldn’t find anything online about it.

Using MVVM-Light for Windows Phone development and Blend. It works fine in Visual Studio, but every time I open one of my pages in Blend I get this error. 

Blend Error: Class is already registered. mvvm-light in Blend

Already registered? I’m using MVVM-Light’s integration with a Simple IoC container to manage my dependencies and so it really leaves me wondering what’s going on here. I know that I only registered this class once.. so what gives?

Fortunately for me, Laurent (the creator of MVVM-Light, fellow MVP, and all around Blend Ninja) is active on Twitter and saw my tweet.

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hmm.. let’s try that…

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and ta-day!

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Design time data working in Blend using MVVM-light!.

Special thanks to Laurent for knowing exactly what I needed to do. Thanks my friend!

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About Caleb Jenkins

Caleb Jenkins is an international speaker, author and 6 time Microsoft MVP award recipient, he currently works for Solera as a Director of Software Development. An entertaining and informative speaker who approaches software from a fresh perspective that spans UX, agile practices and technologies for enterprise customers from across the globe. Leading UX product design teams, coaching multi-team agile transformations and architecting and mentoring at some of the largest companies in the world, As a long time community leader and former Microsoft Developer Evangelist, Caleb is well known for his engaging speaking style, depth of knowledge and creative energy. Founder and Principal Mentor of Proaction Mentors, former UX Manager and Agile Coach, Senior Architect for Six Flags Corporation, Product Architect on a Cloud Marketing Platform, Caleb has made a career out of empowering others while building products and teams that delight customers and solve business needs. You can follow him on twitter (@calebjenkins) or his blog, DevelopingUX.com and if you're still reading this, then you could also subscribe to his blog RSS feed or sign up to receive updates by email