"java.security.cert.CertPathValidatorException: Trust anchor for certification path not found"

Error Message

Note:
The functionalities of ArcGIS Collector, ArcGIS Explorer, and ArcGIS Tracker are now available in ArcGIS Field Maps. There are no new capabilities planned for these apps—all future updates will be focused on Field Maps. Migration is recommended. See ArcGIS Blog: Migrate to Field Maps for more information.

When trying to sign in to access a secured ArcGIS Server feature service on ArcGIS Collector, the following error may be returned:

Error:  
"java.security.cert.CertPathValidatorException: Trust anchor for certification path not found"

When working with ArcGIS Collector, there is the flexibility to work with secured services from ArcGIS Enterprise deployments. The secured feature services can be added to ArcGIS Online with the option to 'Store credentials' checked, or configured to prompt for credentials when opened on the mobile device.

When working with secured layers added as operational layers without storing credentials, ArcGIS Collector displays a warning, 'Secured layers. You need to sign in to access some of the layers in this map.'

Clicking 'View', opens the Layer List, where the Layer name is marked with a triangular warning sign, 'Sign in required'. Normally, a prompt to enter a username and password to authenticate access to the layer is displayed. However in some cases, the option may not be present.

ArcGIS Collector (iOS) does not return any error, however, ArcGIS Collector (Android) displays the error, 'java.security.cert.CertPathValidatorException: Trust anchor for certification path not found'.

Cause

The underlying issue is the SSL Settings on the Web Adaptor configured with the ArcGIS Server site. This setting can be enabled on Internet Information Services (IIS) Manager to require the client to be identified before gaining access to any resource.

Solution or Workaround

1. Identify the Web Adaptor machine name. Open ArcGIS Server Manager.
2. Click the Site tab.
3. Click the Web Adaptor tab and note the machine name from the list of adaptors.

4. Log in to the Web Adaptor machine for ArcGIS Server.
5. Launch Internet Information Services (IIS) Manager and browse to the Web Adaptor name under the default website.
6. Click SSL Settings and under Client certificates, change the setting to Ignore.  Apply the changes.