Windows XP cannot connect to 2012 R2 file shares

Legacy systems that use SMB 1.0 / CIFS may not be able to connect to shares hosted on a system running Windows Server 2012 R2.

Example systems:
Windows XP
Windows Server 2003
Windows Server 2003 R2

First, check to make sure you have “SMB 1.0 / CIFS File Sharing Support” installed. This is the default on Windows Server 2012 R2.

Issue:

The “srv” service may be missing.

Check for this registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\srv

One fix:

1) Remove SMB 1.0 / CIFS File Sharing Support.
2) Reboot.
3) Reinstall SMB 1.0 / CIFS File Sharing Support.
4) Reboot.

The registry key and service should be installed.

You can also try to re-insert the missing registry key:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\srv]
"DisplayName"="@%systemroot%\\system32\\srvsvc.dll,-102"
"ErrorControl"=dword:00000001
"Group"="Network"
"ImagePath"=hex(2):53,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,44,00,\
  52,00,49,00,56,00,45,00,52,00,53,00,5c,00,73,00,72,00,76,00,2e,00,73,00,79,\
  00,73,00,00,00
"Start"=dword:00000002
"Type"=dword:00000002
"Description"="@%systemroot%\\system32\\srvsvc.dll,-103"
"DependOnService"=hex(7):73,00,72,00,76,00,32,00,00,00,00,00