cannot access to my confluence 6.4

[Doha Rouibaa]

Dear Community

So my question is the following , after an upgrade of my confluence i couldn't connect to my plateform . On catalina.out log i have the following message :  Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/catalina/startup/Bootstrap : Unsupported major.minor version 52.0
When i tape Java - version i get this : 
openjdk version "1.8.0_265"
OpenJDK Runtime Environment (build 1.8.0_265-8u265-b01-0ubuntu2~16.04-b01)
OpenJDK 64-Bit Server VM (build 25.265-b01, mixed mode)   but, when i tape for instance sudo apt-get install jre i get this : 
jre is already the newest version (1.7.080-1).   I have looked in so many forums , the only given solutions are dedicated to windows users  and also am not sure if this is the probleme , because according to attlassian https://confluence.atlassian.com/doc/setting-the-java_home-variable-in-windows-8895.html   "In most cases you should set the JRE_HOME environment variable, but if it is not set, Confluence will use JAVA_HOME. " in my JAVA home , it takes the propre JAVA directory of java 1.8  P.S : i am using Confluence 6.10 

Thank you in advance :)

[repi]

@Doha Rouibaa 

You host the confluence on a windows server?
With which routine do you do the install / update?
With the exe installation file or manually with the zip or tar file?

[Doha Rouibaa]

Hello, 

No I use Linux as hostserver.

For the update i make a back_up for my current Confluence and i follow the instructions from the file .bin of the new Confluence that i want to update .

Thank you