WFM not accessible through Microsoft Internet Explorer
Summary: WFM could not be used by customers with Internet Explorer
Impact: All customers using Internet Explorer were affected
Root Causes: The landing page of WFM was accidentally served with a generic mime type. The mime type defines the type of data sent. Browsers use this information to load the data. Microsoft Internet Explorer does not try to detect the content automatically. This produced a downloadable file for users visiting our website instead of a rendered page. Our monitoring systems did not detect this behavior because all requests seemed to be successful on our side. **
Detection: Customer support ticket was created in our community component
Resolution: We updated the mime type we send during requests and patched all of our systems
Lessons Learned: We need to improve our testing for all common browsers
Action Items: We will improve our testing regarding Internet Explorer. In this case the issue was neither detected through automatic testing nor through manual efforts. We have an automatic test suite that has about 20.000 test cases which runs on every change of the affected software component. With this system we try to guarantee that our software is always delivered with best quality.
We take all outages seriously, but we are particularly concerned with outages which affect all customers at once. This incident report is both longer and more detailed than usual precisely because we consider this event so important. We want you to understand why it happened and what we are doing about it. It is our hope that, by being transparent and providing considerable detail, we demonstrate our ongoing commitment to offering you the best product.