Since I installed Firefox 53, everytime I start one of my automated Selenium tests in Firefox a second tab is opened just a moment after launch, which then prevents my test from finding its needed controls on the first tab and ultimately makes it fail. The new tab's url is: https://support.mozilla.org/1/firefox/53.0.2/WINNT/de/insecure-password
The tests work fine in Chrome and Internet Explorer. And there also is no tab opening in when I use Firefox manually. The same problem occurs not only on my local maschine but also on two servers we use as Test Agents for TFS.
I am using C# in Visual Studio 2015 with the packages Selenium.WebDriver and Selenium.Support both in version 3.3, there is a bug that prevents me from using 3.4 (see this question). My Firefox version is 53.0.2, geckodriver is 0.16.1 and Selenium Server Standalone is 3.4.0. I am using the RemoteWebDriver to launch the Browsers.
I've tried finding an about:config value that might disable this new tab or using a custom FirefoxProfile in Selenium, but both to no avail.