Fix RPC Server Unavailable: Windows Troubleshooting Guide

When the dreaded “RPC server unavailable” pops up, it feels like a traffic jam in a city that never sleeps. It can halt backups, freeze printers, and leave virtual disks stuck in limbo. The error cuts through workflows faster than a coffee spill on a keyboard. If you’re an IT pro, admin, or power user, you’ve probably stared at that message more than once.

What Is RPC?

Remote Procedure Call (RPC) is the backbone of Windows networking. It lets processes on different machines talk as if they’re sitting side‑by‑side. When RPC stalls, any operation that relies on remote communication throws that same error.

Common Causes of the RPC Server Unavailable Error

Common culprits include:

Stopped RPC services.
Firewall blocks on ports 135, 139, 445, and dynamic RPC ranges.
DNS resolution failures.
Kerberos/SPN mismatches.
Corrupted system files.

Step‑by‑Step Fixes for Common Scenarios

Open Services – ensure Remote Procedure Call (RPC) and RPC Locator are running.
Check Firewall – create inbound rules for TCP 135, 139, 445 and dynamic ports 49152‑65535.
Verify Network – ping, tracert, nslookup the target.
Test RPC via PowerShell – Invoke‑Command to the host.
Inspect Event Log – look for IDs 1002 or 1014.
If corruption suspected – re‑register rpc.dll.

RPC Fixes for Veeam

Restart Veeam services, verify SMB 2.0+, check SPNs, sync time, open firewall ports.

RPC Fixes for Disk Management

Run diskmgmt.msc locally; for remote, enable Remote Administration, verify SMB share permissions, ensure the disk isn’t full, use diskpart if MMC fails.

RPC Fixes for Printer Setup

Enable Print Spooler, allow RPC over SMB, verify DNS, check Group Policy, restart client.

VPN Considerations

Network hiccups often get tangled with VPN traffic, especially when a VPN like Forest VPN routes traffic through encrypted tunnels that can block RPC ports. VPNs like Forest VPN can silently block RPC ports, turning a simple outage into a network labyrinth.

Quick Checklist

RPC services running
Firewall rules set
DNS resolves
Clocks synced
Services set to auto
SPNs registered
VPN not blocking RPC

With these steps, the RPC server error is no longer a mystery but a solvable puzzle. We’ve walked through each environment, so you can jump back online without a tech support ticket.

If you’re still stuck, Forest VPN’s lightweight, no‑config setup lets you create a dedicated RPC tunnel that bypasses corporate firewalls. Its built‑in port‑forwarding ensures ports 135, 139, 445, and 49152‑65535 always reach the target, eliminating the “RPC server unavailable” headache.

FAQ

Q: Why does RPC fail after a Windows update? A: Updates can disable or restart the RPC service; check the service status and ensure it’s set to Automatic.

Q: Can I disable the firewall for RPC? A: It’s safer to create specific inbound rules for the required ports rather than disabling the firewall entirely.

Q: How do I verify that my DNS is working? A: Use nslookup on the target hostname and confirm it returns the correct IP address.

For more detailed guidance, see our Windows Networking Guide or the official Microsoft support article on RPC Server Unavailable.

Why RPC is the Backbone of Windows Networking

RPC (Remote Procedure Call) lets a program on one computer invoke a function on another as if it were local. On Windows, RPC powers file sharing, printer access, Active Directory, remote administration, backup operations, and disk utilities behind the scenes. When RPC stalls, every one of those services throws an "RPC server unavailable" error, disrupting the entire network.

Common Causes of "RPC server unavailable"

RPC Service or Endpoint Mapper stopped – The service that maps requests (RPC Endpoint Mapper) must run as Automatic.
Firewall blocks ports – TCP port 135 and the dynamic port range 49152‑65535 are required.
DNS or name resolution problems – Incorrect or missing DNS records prevent the client from locating the server.
Network connectivity issues – A broken NIC, mis‑configured VLAN, or cable fault can stop RPC traffic.
Mis‑named or disabled services – Services such as Remote Procedure Call (RPC) and Remote Procedure Call (RPC) Locator may be disabled or set to Manual.

Fixing "RPC server unavailable" in common scenarios

Enable RPC services

Open Services (services.msc).
Find Remote Procedure Call (RPC) and Remote Procedure Call (RPC) Locator.
Set both to Automatic and start them.

Open the required ports

In Windows Defender Firewall, create inbound rules for TCP 135 and the dynamic port range 49152‑65535.
For a domain‑joined machine, make sure the Remote Administration firewall profile is enabled.

Verify DNS resolution

Run nslookup <server-name> to confirm the name resolves to the correct IP.
If it doesn’t, add the correct A record or update the hosts file.

Check network connectivity

Ping the server: ping <server-name>.
Use tracert or pathping to spot packet loss.
Inspect the NIC status in Device Manager.

Confirm RPC Endpoint Mapper is listening

Run netstat -ano | findstr 135 on the server.
If there’s no listening entry, restart the RPC service or reboot.

Checklist to confirm the issue is resolved

RPC and RPC Locator services are running and set to Automatic.
TCP 135 and 49152‑65535 are open in the firewall.
DNS resolves the server name correctly.
Network ping succeeds with no packet loss.
The server’s RPC Endpoint Mapper is listening on port 135.
After making changes, retry the operation that previously reported "RPC server unavailable".

If you’re dealing with the error "virtual disk manager the rpc server is unavailable", these steps will restore communication between the Virtual Disk Manager and the remote host, allowing backups and disk management to resume.

Further reading