This Article Applies to:

Omada SDN Controller (Windows & Linux) V4

Issue Description/Phenomenon:

The SMTP service for the Omada SDN Controllers fails after upgrading to Java_8u291(Windows) or OpenJDK_1.8.0_292(Linux). The phenomenon is that the mail server stops working on the Omada Controller and you may get the error "Send mail exception Could not connect to SMTP host".

A related post described the problem HERE. 

Note: 

If you are not sure which Java version you are using, please refer to the link below to have a check:

https://java.com/en/download/help/version_manual.html

Available Solutions:

TP-Link team has located the problem and will fix the issue in the subsequent updates later. on Controller v5.0.

[Case Closed] Update:

Omada Controller v5.0 (Windows & Linux) has been released to support OpenJDK8 and above version, which has fixed the SMTP issue described here. If this solution post doesn't work for you, your case is probably different. In that case, don't hesitate to click Start a New Thread and elaborate on the problem so that we can try to help you further.

As a temporary solution, you can fix the issue by manually modifying the java configuration file as below:

Open the "java.security" file, find "jdk.tls.disabledAlgorithms" as shown in the following picture,

delete "TLSv1, TLSv1.1," to enable TLSv1 and 1.1, and save the changes;

then restart the Omada SDN Controller.

Note:

• For Windows, the default path of the file is "C:Program Files Javajre1.8.0_291libsecurity" or

"C:Program Files (x86)Javajre1.8.0_291libsecurity".

• For CentOS/Fedora, the default path is "/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.292.b10-1.el7_9.x86_64/jre/lib/security/java.security".
• For Debian/Ubuntu, the default path is "/etc/java-8-openjdk/security/java.security".

Reference: https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8202343