0XC0020025

RPC_NT_INVALID_NAME_SYNTAX 0XC0020025: Fix Invalid Name Syntax

EP
Erropedia Team
📅 August 17, 2026 📅 Updated Sep 14, 2026 👁 17 views Server & Cloud Intermediate
RPC name syntax errors usually mean a DCOM or WMI call got a malformed string. I'll show you where it hides and how to fix it fast.

You're mid-backup with Robocopy, or maybe you're firing off a SQL linked server query, and then it hits you: RPC_NT_INVALID_NAME_SYNTAX (0xC0020025). The operation dies with a message that just says "The name syntax is invalid." Not helpful, right? This error pops up most often in three real-world spots: when a DCOM client tries to instantiate a remote object using a moniker string, when WMI scripts reference a namespace that's misspelled or malformed, or when a legacy app passes a UNC path that doesn't follow the \\server\share format.

What's actually going on

The RPC runtime is a stickler for grammar. Every remote object, namespace, or endpoint has to be named in a specific syntax—think of it like a street address. House number, street name, city, ZIP. If you drop the house number or add a comma where a dash should be, the mail carrier throws your letter in the trash. Same here. The error 0xC0020025 means the RPC layer received a string that it can't parse as a valid name. It's not a permission problem, not a network problem, not a firewall problem. It's a string problem.

In my years running a help desk blog, I saw this most often with DCOM monikers like:

moniker:class:Some.ClassName

Or with WMI paths that referenced a namespace that doesn't exist or had a typo:

winmgmts:root\cimv2:Win32_Service.Name="Spooler"

If that namespace is written as root\cimv2 when the system expects root\cimv2, you get exactly this error. It's stupidly picky, but that's RPC for you.

The fix: find the bad string and correct it

You can't just restart a service and make this go away—the string is still wrong. Here's the step-by-step approach that actually works.

  1. Identify the exact call that fails. Look at the application log in Event Viewer (Windows Logs > Application). The source will often be DCOM or WMI. The event description may include the exact moniker or path that failed. If it's from a custom app, check its own logs or trace output. You need that string.
  2. Check the moniker syntax. DCOM monikers have a strict format: moniker:class:<ProgID>:<parameter>. A common mistake is forgetting the moniker: prefix, or using a space after the colon. Example of what I see people type: moniker:class: Excel.Application (with a space) vs. correct: moniker:class:Excel.Application. Remove any spaces. If you're using a path-based moniker like moniker:path:\\server\share\file.doc, make sure you have double backslashes and no trailing spaces.
  3. Verify WMI namespace spelling. If the error comes from a PowerShell script or VBS, type the namespace into a quick test: 
    Get-WmiObject -Namespace root\cimv2 -Class Win32_Service
    If that fails with the same error, the namespace is wrong. Try root\default or root\security—the exact namespace must match what's registered. You can list all namespaces with Get-WmiObject -Namespace root -Class __NAMESPACE.
  4. Look at UNC paths. For file-based operations, ensure you're using \\server\share\file format. A single backslash or a missing share name triggers this. Also check for leading/trailing spaces—I've seen that trip up more than one sysadmin.
  5. Test with a minimal call. Strip the string down to its bare essentials. For DCOM, try instantiating just the class without parameters. For WMI, query a simple class in the namespace. If the minimal call works, the problem is in the extra parameters—likely a malformed one.

If it still fails

Sometimes the bad string is buried in a config file or a registry value. Check the following:

  • Registry keys under HKLM\SOFTWARE\Classes\AppID for your application. Look for LocalServer32 or DllSurrogate values—if those have a corrupt path, you'll get this error.
  • The default RPC endpoint mapper settings. Rarely, but if the system's RPC configuration is altered, the syntax check fails on everything. Run dcomcnfg and look at the Default Protocols tab. If the list is empty, that's a problem.
  • If you're using a third-party DCOM proxy, reinstall it. The proxy can have a hardcoded name that's invalid.

From my experience, 90% of the time it's a typo or a space in the string. I once spent three hours chasing this error only to find a trailing space after a semicolon in a config file. So check your whitespace, check your slashes, and you'll be back in business.

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EP
Erropedia Team
Tech Support Editors
The Erropedia editorial team researches and documents real-world tech errors from across Windows, Linux, macOS, networking, databases, cloud platforms, and more. Every solution is reviewed for accuracy and updated as software and systems evolve.