If you have an old Android phone, it may be time to really consider an upgrade.

According to a report from Android Police, many secure websites will no longer work on devices with Android versions prior to 7.1.1 Nougat. Here’s what’s happening.

The certification non-profit organization Let’s Encryptrecently announced that its partnership with certification authority IdenTrust will end on Sept. 1, 2021. With no plans to renew, Let’s Encrypt is planning to completely switch over to its own root certificate and stop default cross-signaling for IdenTrust’s on January 11.

In layperson's terms, this means that many secure websites will no longer be compatible with older versions of Android.

This could end up being a problem. As Let’s Encrypt notes, 33.8 percent of Android devices are running these older versions of the operating system. Those devices will experience certificate errors when trying to visit many secure websites starting in 2021.

So, if you were thinking of updating your old Android device, now might be a good time before it becomes obsolete.

However, if you don’t want to upgrade your phone, you may still have options. Let’s Encrypt has recommendedthat old Android device owners download Firefox and use it for their web browsing needs.

"For an Android phone’s built-in browser, the list of trusted root certificates comes from the operating system – which is out of date on these older phones," explains a post on the organization’s website. "However, Firefox is currently unique among browsers – it ships with its own list of trusted root certificates. So anyone who installs the latest Firefox version gets the benefit of an up-to-date list of trusted certificate authorities, even if their operating system is out of date."

But fair warning: That could solve the mobile browsing issues for now, but you may still experience certificate errors when using apps on your old Android device, making an upgrade necessary.