Yes, that's the closure compiler: https://github.com/google/closure-compiler/issues/3280
The effect of the symbol is that no minimizer won't be run, so no CSS and JS minification. We added a request filter to restrict disabling minification to IE11: @Contribute(RequestHandler.class) public static void contributeRequestFilter(OrderedConfiguration<RequestFilter> conf, UserAgentDetector userAgentDetector) { conf.add("IE11-underscore-fix", new RequestFilter() { @Override public boolean service(Request request, Response response, RequestHandler handler) throws IOException { Optional<UserAgent> currentUserAgent = userAgentDetector.current(); currentUserAgent.ifPresent(userAgent -> { Browser browser = userAgent.getBrowser(); if (Browser.IE == browser.getGroup()) { request.setAttribute(TapestryConstants.DISABLE_JAVASCRIPT_MINIMIZATION, Boolean.TRUE); } }); return handler.service(request, response); } }); } UserAgentDetector is a custom service from us, not Tapestry. It could be improved to just blacklist the non-working source files, and not disable it for every JS and IE 11. Ben On Tue, Oct 27, 2020 at 10:30 AM Hakan Sahin <sa...@avetana.de> wrote: > Thank you for your response. > > The error message occurs on core.js(121,20). I put the screenshot and the > cursor shows the position 20 below. > > Disabling MINIFICATION_ENABLED worked. I can not see the error on the > console any more. But did that has an effect for the web app in production > mode? > > I am using Tapestry 5.6.1. > > Thank you and regards, > H.Sahin > Am 27.10.2020 um 10:08 schrieb Ben Weidig: > > Hi, > > does the problem occur in production only, or also in dev? > > We had some issues with Google Closure Compiler and IE11 in the past, > optimizing "too much". > > You could try to disable minification to narrow the problem > down: org.apache.tapestry5.SymbolConstants.MINIFICATION_ENABLED > > Or you can check the core.js file received in the browser, too see the > actual JS that IE11 doesn't like. > > I couldn't recreate your error, even though we're running 5.6.0. But there > weren't changes to coffee files in 5.6.1 as far as I know. > > Ben > > -- Netzgut GmbH Kirchstr. 18 69115 Heidelberg Telefon: +49 6221 39298 53 Telefax: +49 6221 39298 59 E-Mail:b...@netzgut.net Handelsregister: Amtsgericht Mannheim, HRB 709833 Sitz der Gesellschaft: Heidelberg Geschäftsführer: Felix Gonschorek, Benjamin Weidig Ust-IdNr.: DE272871752