Pantheon is updating its platform to align with current IANA standards by removing support for deprecated MIME types that use the x- prefix. This change will be introduced on November 17, 2025.
The following deprecated types have been updated to their modern, IANA-standard equivalents. No action is required for these files unless you have custom code explicitly referencing the old format.
application/mathml+xml mmlapplication/javascript js mjsimage/vnd.microsoft.icon icoimage/bmp bmpapplication/vnd.rar raraudio/mp4 m4avideo/mp4 m4vfont/ttf ttftext/vcard vcfapplication/vnd.amazon.mobi8-ebook mobi
The following deprecated x- prefixed MIME types will be removed entirely from platform support:
text/x-component htcimage/x-jng jngapplication/x-7z-compressed 7zapplication/x-cocoa ccoapplication/x-javascriptapplication/x-java-archive-diff jardiffapplication/x-java-jnlp-file jnlpapplication/x-makeself runapplication/x-perl pl pmapplication/x-pilot prc pdbapplication/x-redhat-package-manager rpmapplication/x-sea seaapplication/x-shockwave-flash swfapplication/x-stuffit sitapplication/x-tcl tcl tkaudio/x-realaudio ravideo/x-flv flvvideo/x-mng mngvideo/x-ms-asf asx asfvideo/x-ms-wmv wmvvideo/x-msvideo aviapplication/x-plist plist
Action
Review any custom code or configurations that utilize the removed MIME types and update them to use their respective IANA-standard equivalents.
If you encounter a file type that IANA does not yet handle, or if you require an alternative configuration, please follow the instructions in our documentation.