# Application Server

Troubleshooting |

This page provides general troubleshooting information regarding some of the issues you may encounter when running the Application Server.

## Network Connectivity

Verify IP connections if the client is unable to communicate with the server. Even if a client has successfully connected to the server in the past, several events could cause unsuccessful attempts at any time; i.e. changed TCP/IP settings, router problems, DNS services down, duplicate IP address on the network, etc.

## Server-Side Issues

Difficulties can be caused by several server-specific issues; i.e. incorrect permission settings, daemon not running, invalid daemon command line syntax, socket in use by another application, daemon starting in the wrong directory, etc.

#### Note:
To maintain settings when moving, upgrading or reinstalling your server, ensure that your configuration files are saved and copied to the appropriate new location. See Server Configuration Files.

The most common problems involve UNIX file permissions. When the Application Server's configuration system is first run, and every time the software is upgraded, the *.pvk files in the Lib/_appserv directory are either created or recreated as required. If the user that you are logged in as has not set a UMASK 000, then these files may not be writable by other users. The Lib/_appserv/sessions.pvk requires Read/Write file permissions for all users for whom sessions will be launched.

File permissions on the PxPlus ACTIVATE.PVX file must be Read/Write, and all utility programs must have at least Read permissions for the user under which the sessions will be run.

## Client-Side Issues

Verify that the client configuration is using the correct domain and password. The client may fail if the server is unreachable, which is a symptom related to Network Connectivity. The client's firewall configuration may be the cause of a failure if programs are unable to receive data from the server.