Communication error with Vaadin 6.8.8

We are experiencing a communication error in this red box in the browser when a % character is inputted into a textfield

Communication problem

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(SyntaxError): missing ) in parenthetical stack: HV@http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:1806 UV@http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:3234 tm@http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:2455 Tm@http://www2..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:3231 d.onreadystatechange<@http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:1762 Rb@http://www2..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:1385 Ub@http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:2704 @http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html:1914 fileName: http://www..fi/App/VAADIN/widgetsets/package.name.widgetset.AppWidgetset/EABD2CCA1B8FDAE1801DD24D9A36DBA9.cache.html lineNumber: 1806 columnNumber: 0 - Original JSON-text: html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>

I have not been able to find a solution so far and migrating to Vaadin 7 is something we would like to avoid at this point. Appears to be a problem with Vaadin’s JS. Any hints?

Any help is greatly appreciated!