How to troubleshoot 'No server is available to process the request' in NCache?

Ensure the NCache Server port (default 9800) is not blocked by a firewall. This is the port where the NCache Service listens for client connections. You can check or change this in the Alachisoft.NCache.Service config files for Windows or Linux.

How to resolve NCache 'Unable to communicate with server node' error?

This error is usually caused by the cluster port being blocked. Ensure the firewall allows communication on the cluster port (starts at 7800 by default). If a port range is specified in the NCache Management Center, all ports in that range must be unblocked.

What to do when NCache Management Center cannot connect to the NCache Service?

Check that the Service port (port 8250) is not blocked by the system firewall. Configure the firewall to permit traffic on this management port to enable local or remote administration.

Troubleshooting

Sometimes a cluster cannot be formed, or cluster nodes are unable to communicate with each other. It may happen when Server and Cluster ports are blocked by a firewall. The following error messages can occur in this case:

Server Communication Error

Error: "No server is available to process the request"

Error: "Unable to communicate with server node"

Error: "The NCache Management Center is unable to connect with the NCache Service"

Note

Check your firewall settings using the details in the NCache Install Guide.

Workaround

For the error, No server is available to process the request, make sure that the Server port (at which the NCache Service starts and accepts different client connections) is not blocked by a firewall. The default value of this port is 9800. You can change the default value from the cache server configuration file found in NCache as follows:
- Windows: Alachisoft.NCache.Service.exe.config located in %NCHOME%\bin\service
- Linux: Alachisoft.NCache.Daemon.dll.config located in /opt/ncache/bin/service
For the error, Unable to communicate with server node, check to see that the cluster port is permitted by your firewall. A cluster port is a port at which nodes in a cluster communicate. You can change the default value of these ports from the NCache Management Center. If you have specified a port range in the NCache Management Center, unblock all ports in the range.
For the error, The NCache Management Center is unable to connect with the NCache Service, ensure that your system's firewall is disabled and not blocking the Service port (port number 8250). Unblock the Service port from the system firewall.

Cache Not Visible in NCache Management Center

Sometimes a clustered cache may already exist on a server but does not appear in the NCache Management Center.

Workaround

If the cache already exists and is running on a server node, add it to the NCache Management Center without recreating it:

Launch the NCache Management Center by browsing to http://localhost:8251 or <server-ip>:8251.
In the left navigation bar, click on Clustered Caches or Local Caches, based on the cache for which you need to configure the settings. The page shows any existing clustered caches on your machine and additional details like Topology, Servers, and Server Platform.
To add a registered clustered cache, click on Add.