When "There is a process already using the admin port 4848", but it is not true 📎
When you try to start Payara 5 / GlassFish with:
asadmin start-domain
...and you get the following error:
There is a process already using the admin port 4848 -- it could be another instance of Payara Server or Payara Micro.
Command start-domain failed.
although there is no running Java process and the port is not occupied, you hostname is probably not pingable:
ping $(hostname)
output: Request timeout
Solution:
Add the following line to the /etc/hosts file:
127.0.0.1 [YOUR_NOT_PINGABLE_HOSTNAME]