Deployment error:Starting of Tomcat failed, the server port 8080 is already in use

goto command prompt

netstat -aon

for linux

netstat -tulpn | grep 'your_port_number'

it will show you something like

 TCP    192.1.200.48:2053      24.43.246.60:443       ESTABLISHED     248
 TCP    192.1.200.48:2055      24.43.246.60:443       ESTABLISHED     248
 TCP    192.1.200.48:2126      213.146.189.201:12350  ESTABLISHED     1308
 TCP    192.1.200.48:3918      192.1.200.2:8073       ESTABLISHED     1504
 TCP    192.1.200.48:3975      192.1.200.11:49892     TIME_WAIT       0
 TCP    192.1.200.48:3976      192.1.200.11:49892     TIME_WAIT       0
 TCP    192.1.200.48:4039      209.85.153.100:80      ESTABLISHED     248
 TCP    192.1.200.48:8080      209.85.153.100:80      ESTABLISHED     248

check which process has binded your port. here in above example its 248 now if you are sure that you need to kill that process fire

Linux:

kill -9 248

Windows:

taskkill /f /pid 248

it will kill that process

If you are behind a proxy server this issue could happen i had the same issue and was solved by: Preferences -> General -> Proxy Settings -> No Proxy.

"Maybe the tomcat ready-message was sent to the proxy - and never reached the IDE."

found @: https://netbeans.org/bugzilla/show_bug.cgi?id=231220

I had the same problem when trying to deploy, tomcat failed to restart as Tomcat instance was running. Close the IDE and check TASk Manager - kill any javaw process running, that solved the problem for me.