How to resolve grails-resolving-server-failed-to-start-for-port-8080-address-already-in-use

On Linux:

step1: if your server port already running at port 8080 then, firstly we have to kill this process for this open your terminal and type

lsof -w -n -i tcp:8080

which shows all the list of open file which is running at port 8080. if you type
lsof -w -n -i tcp:9090 if your server is running with port 9090 which shows all the list of open file which are running at port 9090. Here, lsof stand for ls = list and of = opened file. You can see list with pid number.

step2: type sudo kill -9 6911 where 6911 is pid number. Here 9 has its own meaning which is defined as kill command "SIGKILL" you can see this by type in terminal as kill -l . You can use -SIGKILL instead of -9.

step3: run your application. 

On Windows:

- Open and run command prompt as administrator and type following command:

   

   netstat -ano | findstr :8080

This command will find and list the process that uses this port.

Now, we need to kill the process, for this use following command:

   taskkill /pid 5884 /f

Where 5884 is the PID number. Use your PID number which is obtained previously.