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KNOWN LIMITATIONS

KNOWN_LIMITATIONS.md

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Known limitations

  • Mobile Detect script was designed to detect mobile devices. Implicitly other devices are considered to be desktop.
  • User-Agent and HTTP headers sniffing is a non-reliable method of detecting a mobile device.
  • If the mobile browser is set on Desktop mode, the Mobile Detect script has no indicator (eg. a group of strings) that would allow it to detect that the device is mobile.
  • Ipad 2019 is being recognized as a desktop because of Safari's default Request Desktop Website setting. See details and possible workaround #820
  • Some touchscreen devices (eg. Microsoft Surface) are tough to detect as mobile since they can be used in a laptop mode. See: #32, #461, #667
  • Some mobile devices (eg. IPadOS, Google Pixel Slate). See: #795, #788
  • Detecting the device brand (eg. Apple, Samsung, HTC) is not 100% reliable.
  • We don't monitor the quality of the 3rd party tools based on Mobile Detect script. We cannot guarantee that they are using the class properly or if they provide the latest version.
  • Version 2.x is made to be PHP 5.3 compatible because of the backward compatibility changes of PHP.
  • There are hundreds of devices launched every month, we cannot keep a 100% up-to-date detection rate.
  • The script cannot detect the viewport, pixel density or resolution of the screen since it's running server-side.
  • Full-page edge / proxy caches that don't key on User-Agent will defeat server-side detection. When a CDN or page-cache plugin stores the rendered HTML and serves it to subsequent visitors without varying by User-Agent, the device class baked into the first cached response is delivered to everyone — PHP (and Mobile Detect) never run on a cache hit. This is an architectural property of full-page caches, not a bug in this library, and applies equally to any server-side branching (geo redirects, A/B tests, header-based locale, etc.). Known examples reported against this project:
    • WP Engine Edge Full Page Cache — disable it on routes that branch on UA. See #980.
    • W3 Total Cache (WordPress plugin). See #447.
    • Cloudflare + Google Signed Exchanges (SXG). See #945.
    • Possible mitigations belong to the host/CDN config, not the library: disable the cache on UA-sensitive routes, add Vary: User-Agent if the CDN honors it, classify UA at the edge (Cloudflare Workers, Akamai EdgeWorkers, Vercel Middleware) and use the result as part of the cache key, or move device-specific logic client-side.