Unable to send file to HTTPS URL -

Configured new trading partner that has HTTPS URL, and imported their cert. Note, all existing trading partners currently working are HTTP.

Receiving error below. Any help would be appreciated.

mendAS2-1690208730632-2579@FIDELAS2_AS2_xxxx: Connection problem, failed to transmit data.
[Jul 24, 2023 9:25:31 AM] mendAS2-1690208730632-2579@FIDELAS2_AS2_xxxx: Will retry to send transmission after 30s, retry 1/10.
[Jul 24, 2023 9:25:31 AM] mendAS2-1690208730632-2579@FIDELAS2_AS2_xxxx: MessageHTTPUploader.performUpload: [SSLHandshakeException]: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

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