Since Spring 5.2 the Cors Handling is changed, if the request is not a cors request. This impacts the loading of the fonts in IE9. Caching fonts in combination with IE9 is kind of unstable. Adding the the "Vary" headers on the fonts breaks the loading of the fonts after a reload of the page.
Best option is that visitors don't use IE 9 anymore, but I'm afraid I can't force that. It would be fine if this impacts only the font type. Unfortunately also some icons are loaded with a font, so this impacts functionality on some pages.
Comment From: sdeleuze
Hi, as described in the related issue, these changes have been done on purpose and I am afraid this IE9 bug is not something we should handle on Spring Framework side. Notice that IE9 is unsupported since 1/12/16 and that Microsoft itself recommends upgrading. You can maybe write a filter to implement the behavior you need.
Comment From: majnaber
I reproduced the same problem with IE 11, which is still supported by microsoft
Comment From: sdeleuze
Then I guess Microsoft should fix this bug even if the reporting process is not clear to me.
Comment From: sdeleuze
As hinted before, you should be able to write a filter or an interceptor which, based on the user-agent, removes the Vary headers for Internet Explorer.
Comment From: majnaber
I fixed it with added the ShallowEtagHeaderFilter for fonts (but it is probably better to do this only it for Internet Explorer)