ODK Collect fails to download forms - User certificate not trusted on Android 8

[Grzesiek2010]

Hi @Jean_Juste_Harrisson
Welcome to ODK forum. When you get a chance, please introduce yourself here.

@Jean_Juste_Harrisson

Is there an official way to configure ODK Collect to trust user-installed certificates?

There is no official way.
Starting from Android 7+, apps do not trust user-installed certificates by default. ODK Collect does not provide any setting or UI option to enable trust for certificates installed in the user’s certificate store.

@Jean_Juste_Harrisson

Could a build flag or setting be added to allow user certificates for self-hosted servers?

This is possible only via a custom build.
You can create a custom network_security_config in ODK Collect that explicitly trusts user-installed certificates.

@Jean_Juste_Harrisson

Is there a recommended approach for organizations using internal CAs with non-rooted devices?

There is no official way. On non-rooted devices, ODK Collect cannot trust internal or user-installed certificates. The only options are using a public certificate (e.g., Let’s Encrypt) or a custom build of Collect that trusts your internal CA.