ArcGIS Field Maps (Android): Connection error. The server you are trying to connect to is using an untrusted certificate

Error Message

In ArcGIS Field Maps, attempts to connect to the Portal for ArcGIS client on an Android mobile device fail and return the following error message:

Error:
Connection error
The server you are trying to connect to is using an untrusted certificate

Cause

The Secure Sockets Layer (SSL) certificate chain is not trusted. If the SSL certificate is not trusted, ArcGIS Field Maps cannot establish a connection to ArcGIS Enterprise, resulting in the error. On iOS, the system automatically recognizes trusted certificates, requiring no additional steps. However, on Android, even if ArcGIS Server is configured with a trusted certificate, both the server and the device must have the certificate installed for the connection to work.

Solution or Workaround

Install the SSL certificate on a single Android mobile device

1. Download the SSL certificate for the secured portal. Refer to ArcGIS Blog: Learn How to Download a SSL Certificate for a Secured Portal for instructions.
2. Transfer the downloaded SSL certificate to the Android mobile device. For example, send the SSL certificate from the machine to the mobile device via email.
3. Install the SSL certificate on the Android mobile device. Refer to ArcGIS Blog: Learn How to Install a SSL Certificate for a Secured Portal on a mobile device for instructions.

Import the SSL certificate on a load balancer or reverse proxy for multiple Android mobile devices

Note:
Contact the organization's IT department to implement the following workflow.

For multiple mobile devices or users, import the intermediate certificate(s) to the web server at the edge of the network path. For example, if the ArcGIS Enterprise portal is behind a load balancer or reverse proxy, ensure the intermediate certificate is available on the load balancer or reverse proxy. Additionally, if the ArcGIS Enterprise portal's web adaptor is directly exposed, import the intermediate certificate(s) into the Certificates snap-in window in Microsoft Management Console (MMC) in the local computer's Intermediate Certification Authority's store.