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Let's Encrypt root certificate expiration: how to continue using Diawi on Android <7.1.1

On and all our subdomains, we use Let's Encrypt to generate SSL certificates and provide navigation through secure HTTPS connexions. However, on September 30, 2021, the root certificate used by Let's Encrypt to sign their SSL certificates has expired on some older systems like Android system <7.1.1.

To continue using Diawi (and many many other websites) on those older Android devices, there is a solution!

When you navigate to with Safari, if you get a security error like NET::ERR_CERT_AUTHORITY_INVALID or NET::ERR_CERT_DATE_INVALID: you are affected. You could temporarily accept the SSL exception in the browser, but the error will appear again later and on each of our subdomains, which is not practical.

In order to visit Diawi and install apps, the solution is to download and install the new root certificate manually.

  1. Download it from the official Let's Encrypt address:
  2. Open the file with Certificate Installer
  3. You can name it ISRG ROOT X1 as it is it's official name

That's it. The new certificate is valid until 2035 and you are able to continue using Diawi.

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About Greg
Paris, France Website
App deployment ninja, maintainer of Diawi and huge coffee lover.