升级时出现以下错误。可能是什么原因？请帮忙。
Property url: https://aaa.com:8080/download/aa/bb_2_6_3.exe
Backing up C:\Windows\system32\config\systemprofile\Documents\bb_2_6_3.exe
Download: https://aaa.com:8080/download/aa/bb_2_6_3.exe to C:\Windows\system32\config\systemprofile\Documents\bb_2_6_3.exe; size: 332930560 bytes
[ERROR] com.install4j.runtime.installer.helper.content.Md5Checker: could not get md5sums
[ERROR] com.install4j.runtime.beans.actions.net.DownloadFileAction [ID 63]: javax.net.ssl.SSLProtocolException: handshake alert: unrecognized_name
javax.net.ssl.SSLProtocolException: handshake alert: unrecognized_name
at sun.security.ssl.ClientHandshaker.handshakeAlert(Unknown Source)
at sun.security.ssl.SSLSocketImpl.recvAlert(Unknown Source)
at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at com.install4j.runtime.installer.controller.Controller.handleCommand(Controller.java:195)
at com.install4j.runtime.installer.controller.Controller.start(Controller.java:94)
at com.install4j.runtime.installer.Application.runApplication(Application.java:71)
at com.install4j.runtime.installer.Application.main(Application.java:35)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.exe4j.runtime.LauncherEngine.launch(LauncherEngine.java:65)
at com.exe4j.runtime.WinLauncher.main(WinLauncher.java:101)
at com.install4j.runtime.launcher.WinLauncher.main(WinLauncher.java:26)
[INFO] com.install4j.runtime.beans.actions.net.DownloadFileAction [ID 63]: Finished action at 2018-06-27T15:34:59