This article was originally written in 2008, when after the installation of Microsoft Windows XP Service Pack 2 (SP2) some communication programs between PCs no longer worked.
Today, with the Windows 7, Windows Server and Windows 10 versions, the article is still supportive to resolve the error that the PC is unable to connect to the host and above all that the RPC server is not available ".
The area in which this error occurs is in the communication between two computers when you want to use a communication program.
This is an error related to Windows security settings, which need to be loosened in some cases.
In particular, it refers to a problem with the internal Windows firewall and DCOM security, of remote access to the system.
Step 4 is the most important one in this article, which should resolve the RPC error not available
Here's how to reconfigure Windows security settings. (They are to be carried out in the order indicated).
1) Make sure that Windows Firewall is activated
1.1 Log on to the host computer with administrator privileges.
1.2 From the Start menu, Click Settings> Control Panel.
1.3 If you are using classic view, click on Windows Firewall. Otherwise, click Security Center and in the "Manage security information for:" section click Windows Firewall.
1.4 Select Active (recommended).
2) Add the non-working program to the Windows Firewall exception list .
2.1 On the Exceptions tab, click Add a program.
2.2 Select the program from the list.
2.3 If the two PCs are on the same network (subnet), click Change Scope and select Only the local network (subnet).
2.4 Click OK, then click OK again.
2.5 In the Programs and Services list, make sure the box next to the program is checked.
2.6 Click OK and close the Control Panel.
3) Activate the Remote Administration traffic through the firewall by enabling RPC and DCOM
3.1 From the Start menu, select All Programs> Accessories> Command Prompt.
3.2 Type netsh
3.3 Type firewall
3.4 If the two PCs are located on the same subnet, type:
set service REMOTEADMIN ENABLE SUBNET
If the subnet is different for the two computers, type:
set service REMOTEADMIN ENABLE ALL
3.5 Type show service and verify that the Remote Administration option is enabled.
3.6 Type exit and then exit again.
4) Enable remote access to DCOM services for all computers for users who use anonymous access
4.1 From the Start menu, search for administration tools which are also found Click Settings> Control Panel.
4.2 Double-click Component Services.
4.3 In Console root directory, open Component Services> Computers> Local Computer (in Windows 10)
4.4 If a security warning appears, click Unlock.
4.5 Right-click on Local Computer (or My Computer on Windows 7 and XP) and click on Properties.
4.6 In the Properties dialog, open the COM Security tab, in the Access permissions group, click Change limits .
4.7 In the Access authorization dialog box, choose Anonymous access, and select Allow for the Remote access item.
4.8 Click OK, then click OK again.
4.9 Close the Component Services and Administrative Tools windows.
Today, with the Windows 7, Windows Server and Windows 10 versions, the article is still supportive to resolve the error that the PC is unable to connect to the host and above all that the RPC server is not available ".
The area in which this error occurs is in the communication between two computers when you want to use a communication program.
This is an error related to Windows security settings, which need to be loosened in some cases.
In particular, it refers to a problem with the internal Windows firewall and DCOM security, of remote access to the system.
Step 4 is the most important one in this article, which should resolve the RPC error not available
Here's how to reconfigure Windows security settings. (They are to be carried out in the order indicated).
1) Make sure that Windows Firewall is activated
1.1 Log on to the host computer with administrator privileges.
1.2 From the Start menu, Click Settings> Control Panel.
1.3 If you are using classic view, click on Windows Firewall. Otherwise, click Security Center and in the "Manage security information for:" section click Windows Firewall.
1.4 Select Active (recommended).
2) Add the non-working program to the Windows Firewall exception list .
2.1 On the Exceptions tab, click Add a program.
2.2 Select the program from the list.
2.3 If the two PCs are on the same network (subnet), click Change Scope and select Only the local network (subnet).
2.4 Click OK, then click OK again.
2.5 In the Programs and Services list, make sure the box next to the program is checked.
2.6 Click OK and close the Control Panel.
3) Activate the Remote Administration traffic through the firewall by enabling RPC and DCOM
3.1 From the Start menu, select All Programs> Accessories> Command Prompt.
3.2 Type netsh
3.3 Type firewall
3.4 If the two PCs are located on the same subnet, type:
set service REMOTEADMIN ENABLE SUBNET
If the subnet is different for the two computers, type:
set service REMOTEADMIN ENABLE ALL
3.5 Type show service and verify that the Remote Administration option is enabled.
3.6 Type exit and then exit again.
4) Enable remote access to DCOM services for all computers for users who use anonymous access
4.1 From the Start menu, search for administration tools which are also found Click Settings> Control Panel.
4.2 Double-click Component Services.
4.3 In Console root directory, open Component Services> Computers> Local Computer (in Windows 10)
4.4 If a security warning appears, click Unlock.
4.5 Right-click on Local Computer (or My Computer on Windows 7 and XP) and click on Properties.
4.6 In the Properties dialog, open the COM Security tab, in the Access permissions group, click Change limits .
4.7 In the Access authorization dialog box, choose Anonymous access, and select Allow for the Remote access item.
4.8 Click OK, then click OK again.
4.9 Close the Component Services and Administrative Tools windows.
