Win32 Error: The RPC Server is Unavailable

This blog post provides idea about RPC server and a solution for this issue Win32 Error: The RPC Server is Unavailable.

Win32 Error: The RPC Server is Unavailable

Getting Started

The RPC server is unavailable error occurs whenever you windows machine is trying to connect with other connected or remote devices. Devices mean it can be anything a computer or a printer etc.

I wrote this post after I faced the exception when my application was trying to connect with a printer available in intranet, The exception was like this

The RPC Server is Unavailable

Cause of the error

Basically, the error occurs when communication between client and server breakdowns. The RPC server plays key role to maintain communication between client-servers. Whenever the RPC server is not accessible or responsive due to various reasons, the communication breakdowns.

Certain services are responsible to make smooth functioning of the server and that services should be running smoothly in the background.

The common reason of the RPC Server is Unavailable:

1. If the remote device is actually down.
2. If the Network connection between the OpManager server and remote machine is down.
3. Malfunctioning the RPCSS Service.
4. Firewall is blocking the connection between OpManager Server and the remote machine.
5. If the Internet Protocol Version 6(TCP/IPv6) is disabled.
6. If the File and Printer Sharing component is disabled.
7. If the DNS cache has issue.
8. If the startup settings preventing the RPCSS service from loading.
9. If the related registry files have issue.

Solutions:

Follow the below each step till the problem is resolved.

1. Find the RPCSS service in the service window and restart it.
   • On your Keyboard, press Windows + R key together
   • Inside the Run dialog, type service.msc then click on OK button.
   • The Services window will appear.Locate the Remote Procedure Call (RPC) service in the Service Window.
   • Right click on Remote Procedure Call (RPC) Then click on Restart from the menu.
   • Check for the DCOM Server Process Launcher and RPC Endpoint Mapper service, ensure that both are running, and their startup type is set to Automatic.
2. Check whether the RPC and related ports are not block by Firewall.
   • Press Windows + R key on your keyboard.
   • Type control inside the Run dialog then click on ok button.
   • Click system and Security
   • Locate the Allow an app through Windows Firewall option under the Windows Defender Firewall Section.
   • Locate Remote Assistance and make sure both its Public and Private boxes are checked.
   • Then click on Save and restart PC.
3. Boot your PC using normal startup.
   • Search for the System Configuration app and Open it. 
   • In the General tab, ensure Normal startup is selected. If it isn’t, select it, then click OK and restart your PC to see if the problem is resolved.
4. Enable IPv6 and file and Printer sharing
   • Open the Run dialog by pressing the Windows + R kay then type ncpa.cpl and press Enter key.
   • The network connections window will open where you will get list of available network connections.
   • Right-click your network connection → Properties.
   • Check the following boxes, then click OK.
   • File and Printer Sharing for Microsoft Networks
   • Internet Protocol Version 6 (TCP/IPv6)
   • If the problem still not resolved, then update the network adapter drive.
5. Flush DNS cache
   • Run the Command Prompt with administrator rights.
   • Type ipconfig/flushdns then press Enter key on your keyboard.
6. Edit Registry Settings
   • Log in as Administrator.
   • Press Windows +R key then type regedit and press Enter key.
   • Back up your registry by going to File → Export…
   • Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RpcSs and double-click on Start.
   • Set Value data to 2 and click OK.
   • Repeat step 4 (with Value data : 2) for the following Registry keys:
     • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DcomLaunch
     • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RpcEptMapper
   • Restart your PC and see if the problem is resolved.

You may get the exception with below log during logon to the domain computers.

 The system cannot log you on due to the following error: The RPC server is unavailable  

The solution is:

1. Verify correct DNS settings.
2. Verify correct Time and Time Zone settings.
3. Verify that "TCP/IP NetBIOS Helper" is running and set to auto start after restart.
4. Verify that "Remote Registry" is running and set to auto start after restart.
5. Reboot the computer after changing the required settings.

Remote Procedure Call (RPC)Server

RPC Server is a protocol that enables communication between programs or processes on different systems in a network. It allows a program to cause a procedure or subroutine to execute in another address space, typically on a remote server.

It is used for building distributed client-server applications, where a client can request services or perform operations on a remote server.

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