I have installed Google App Engine plugin for Eclipse Indigo. I have created new Web Application Project with auto generated sample code. I unchecked "use Google Web Toolkit" when creating a project. My project looks as described here: [Google App Engine HTTP Error 403](https://stackoverflow.com/questions/11365100/google-app-engine-http-error-403)

When building the project, I get the following error:

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> Errors occurred during the build.
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> Errors running builder 'Google App Engine Project Change Notifier' on project 'Test
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> NO\_MODIFICATION\_ALLOWED\_ERR: An attempt is made to modify an object where modifications are not allowed.
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> 
> 

I can run the servlet on the localhost, without any problems, however when I deploy the application, it doesn't work. Logs show:

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> Uncaught exception from servlet
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> 
> java.lang.UnsupportedClassVersionError: test/Test : Unsupported major.minor version 51.0
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> 
>