An update site that has been working is now failing with the exception below.  It is trying to read p2.index.  This file does not exist in the composite repo nor the product repo.  I created one with minimal contents and receive the same
 error.
 
Any suggestions on how to debug?
Thanks
Timothy
 
20171105 00:15:08.536 11548  ERROR com.easa.acmotor.base.BusinessStatusHandler - uncaught exception: org.eclipse.equinox.p2.transport.ecf : Connection to http://www.xxx.com/sites/motordb_update/repository/p2.index failed on sun.security.validator.ValidatorException:
 PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target. Retry attempt 0 started
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
                at sun.security.ssl.Alerts.getSSLException(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.SSLSocketImpl.fatal(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.Handshaker.fatalSE(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.Handshaker.fatalSE(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.ClientHandshaker.serverCertificate(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.ClientHandshaker.processMessage(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.Handshaker.processLoop(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.Handshaker.process_record(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.SSLSocketImpl.writeRecord(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.AppOutputStream.write(Unknown Source) ~[na:1.8.0_60]
                at org.apache.http.impl.io.AbstractSessionOutputBuffer.flushBuffer(AbstractSessionOutputBuffer.java:159) ~[na:na]
                at org.apache.http.impl.io.AbstractSessionOutputBuffer.flush(AbstractSessionOutputBuffer.java:166) ~[na:na]
                at org.apache.http.impl.AbstractHttpClientConnection.doFlush(AbstractHttpClientConnection.java:272) ~[na:na]
                at org.apache.http.impl.AbstractHttpClientConnection.flush(AbstractHttpClientConnection.java:277) ~[na:na]
                at org.apache.http.impl.conn.AbstractClientConnAdapter.flush(AbstractClientConnAdapter.java:201) ~[na:na]
                at org.apache.http.protocol.HttpRequestExecutor.doSendRequest(HttpRequestExecutor.java:239) ~[na:na]
                at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:121) ~[na:na]
                at org.apache.http.impl.client.DefaultRequestDirector.tryExecute(DefaultRequestDirector.java:685) ~[na:na]
                at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:487) ~[na:na]
                at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:863) ~[na:na]
                at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82) ~[na:na]
                at org.eclipse.ecf.provider.filetransfer.httpclient4.HttpClientRetrieveFileTransfer.performConnect(HttpClientRetrieveFileTransfer.java:1084) ~[na:na]
                at org.eclipse.ecf.provider.filetransfer.httpclient4.HttpClientRetrieveFileTransfer.access$0(HttpClientRetrieveFileTransfer.java:1075) ~[na:na]
                at org.eclipse.ecf.provider.filetransfer.httpclient4.HttpClientRetrieveFileTransfer$1.performFileTransfer(HttpClientRetrieveFileTransfer.java:1071) ~[na:na]
                at org.eclipse.ecf.filetransfer.FileTransferJob.run(FileTransferJob.java:74) ~[na:na]
                at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) ~[na:na]
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
                at sun.security.validator.PKIXValidator.doBuild(Unknown Source) ~[na:1.8.0_60]
                at sun.security.validator.PKIXValidator.engineValidate(Unknown Source) ~[na:1.8.0_60]
                at sun.security.validator.Validator.validate(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.X509TrustManagerImpl.validate(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.X509TrustManagerImpl.checkTrusted(Unknown Source) ~[na:1.8.0_60]
                at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source) ~[na:1.8.0_60]
                ... 24 common frames omitted
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
                at sun.security.provider.certpath.SunCertPathBuilder.build(Unknown Source) ~[na:1.8.0_60]
                at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(Unknown Source) ~[na:1.8.0_60]
                at java.security.cert.CertPathBuilder.build(Unknown Source) ~[na:1.8.0_60]
                ... 30 common frames omitted