Exception: org/postgresql/Driver : Unsupported major.minor version 52.0

change jdk version use openjdk-8


#update-alternatives –config java


Magento Admin Login Page “Error 404 Not Found”

Open PhpMyAdmin and run the following query in your database:-

UPDATE `core_store` SET store_id = 0 WHERE code='admin';
UPDATE `core_store_group` SET group_id = 0 WHERE name='Default';
UPDATE `core_website` SET website_id = 0 WHERE code='admin';
UPDATE `customer_group` SET customer_group_id = 0 WHERE customer_group_code='NOT LOGGED IN';

Increase Memory Heap Size in Apache Tomcat

Option 1:

Open the catalina.sh script file under $CATALINA_HOME/bin/catalina.sh directory assign it,

export CATALINA_OPTS="-Xms128M -Xmx512M"


or simply export,

export CATALINA_OPTS=”-Xms128M -Xmx512MB”


The heap size has been set to Minumum 128MB and maximum 512MB

Option 2:


Another option is create a setenv.sh file and add below line,

export CATALINA_OPTS=”${CATALINA_OPTS} -Djava.awt.headless=true -Dorg.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER=true -Dmail.mime.decodeparameters=true -Xms128m -Xmx512m -XX:PermSize=256m -XX:MaxPermSize=950m -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled”


export CATALINA_OPTS="-Xms128M -Xmx512MB"

You might restart tomcat server,

make sure the memory is increased by

ps aux | grep java