Common exceptions during installation and their resolutions

While installing vREST Enterprise server, there are some common exceptions which might occur and their resolutions are as follows:

1. ERROR:  Licence key not found. Please provide licence key.
   1. This is the expected error when you execute the vREST Enterprise binary for the first time.
   2. Just access the vREST Enterprise server from the public facing URL and setup the licence.
   3. Once the enterprise licence is installed and if you execute the binary again in future then this error will not occur.
2. Error: listen EADDRINUSE :::<PORT_NUMBER>
1. Either another vREST enterprise server is running on port <PORT_NUMBER> or any other service is running on port <PORT_NUMBER>.
2. If another vREST Enterprise server is already running, then you may find the process id and kill the process.
1. You may find out the process id by using the following command:
   ps -eaf | grep "vrest"
2. And kill the process with the following command:
   kill -9 <PROCESS_ID>
3. And now start the enterprise server again.
3. Or If any other service is running on port <PORT_NUMBER>, then you may change the port number of vREST Enterprise server in the config.json file.
3. MongoError: not authorized on <DB_NAME> to execute command
   
   1. You have configured the username and password for MongoDB database, but you might have not configured them in database connection string in config.json file.
   2. Please configure the MongoDB connection string as per the format given in this document `MongoDB Connection String`.