Could not publish server configuration error

Sometimes when I save som file Spring tools suite give the error below. Nevertheless STS let me run and open the application via the browser, It happen when I open a Vaadin composite, its pretty annoying.

Could not publish server configuration: C:\Users\diego\Documents\TRABAJO\springsource\WS.metadata.plugins\org.eclipse.wst.server.core\tmp0\conf\server.xml (The requested operation cannot be performed on a file with a user-mapped section open).
C:\Users\diego\Documents\TRABAJO\springsource\WS.metadata.plugins\org.eclipse.wst.server.core\tmp0\conf\server.xml (The requested operation cannot be performed on a file with a user-mapped section open)

information:
STS 4.2
Using a maven project vaadin-archetype-application
Vaadin plugin experimental
Apache tomcat 7

Thanks!
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