ERR_FAILED is a general error code that can be displayed if the Chromium code is not able to pinpoint the exact cause of the problem.
There are over 1000 references to this particular error in the code, in many areas of the code, including the renderer code, so it is not possible to say what caused the error, unless the text in the error page (which I, at least, am not able to understand; general request: temporarily change UI language to English if the issue can be reproduced) mentioned something specific.