System.err: javax.net.ssl.SSLHandshakeException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.

I have SSLHandshakeException when I try to download file. How to resolve it? Full log:

javax.net.ssl.SSLHandshakeException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.org.conscrypt.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:361)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.Connection.connectTls(Connection.java:235)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.Connection.connectSocket(Connection.java:199)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.Connection.connect(Connection.java:172)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.Connection.connectAndSetOwner(Connection.java:367)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:130)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:329)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:246)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:457)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:405)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:521)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getResponseCode(DelegatingHttpsURLConnection.java:105)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at vn.hunghd.flutterdownloader.DownloadWorker.downloadFile(DownloadWorker.java:279)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at vn.hunghd.flutterdownloader.DownloadWorker.doWork(DownloadWorker.java:193)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at androidx.work.Worker$1.run(Worker.java:85)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
2021-01-13 12:40:46.514 20619-21138/com.action.buhsoft W/System.err: at java.lang.Thread.run(Thread.java:776)
2021-01-13 12:40:46.515 20619-21138/com.action.buhsoft W/System.err: Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.

Start by reading DownloadWorker.java at lines 279 and 193, then trace the HttpsURLConnection request shown in the log. Reproduce the download failure with the reported certificate error and define done as a successful download without the SSLHandshakeException.

Written by the indexing model from the issue text.