Fix ERROR_CLUSTER_INVALID_STRING_FORMAT (0x0000171D) Fast

You're staring at a cluster error that makes no sense.

It's the ERROR_CLUSTER_INVALID_STRING_FORMAT (0x0000171D). The error message says an input string isn't in a valid format for the data it represents. Usually pops up when you try to bring a resource online, create a new resource, or run cluster validation. I've seen it on Server 2016 and 2019 clusters most often, but it can hit any version. The good news: you don't need to rip out the cluster and start over. Here's the fix.

The Fix: Run Cluster Resource Validation and Repair Names

1. Open PowerShell as Administrator on any cluster node.
2. Run this command to check all resource names and dependencies:

   Get-ClusterResource | Format-List Name, ResourceType, State

3. Look for any resource with a name that contains spaces, special characters like @#$%, or leading/trailing spaces. Those are the culprits. Also check names that are ridiculously long (over 200 characters).
4. To fix a bad name, use the Set-ClusterParameter cmdlet. For example, if a resource named "File Server (Sales)" has a trailing space, rename it:

   Get-ClusterResource "File Server (Sales) " | % { $_ | Set-ClusterParameter -Name Name -Value "File Server Sales" }

5. After fixing all suspect names, run cluster validation again:

   Test-Cluster

   If validation passes, you're good. If not, move to the next section.

Had a client last month whose entire file server cluster went offline because someone added a period at the end of a disk witness name. That single period broke the string format. Fix took 30 seconds once we found it.

Why This Happens

Cluster resources store their names and dependency strings as Unicode text. The cluster service parses these strings internally, and it expects a strict format: alphanumeric characters, hyphens, underscores – no whitespace except single spaces between words. No tabs, no line breaks, no non-printable characters. The error 0x0000171D fires when the parser hits a character it can't interpret. Common triggers:

• Copy-pasting a resource name from a spreadsheet that includes a hidden tab or line feed
• A dependency string that includes a trailing comma or semicolon
• Quorum witness path with invalid characters like a tilde ~ or backslash at the end
• Third-party backup or monitoring tools that modify cluster object names directly

Less Common Variations and Their Fixes

Dependency Strings Are Truncated or Corrupt

Sometimes the resource name looks fine, but the dependency string has a bad format. Run:

Get-ClusterResourceDependency

Look for entries that show garbled text, like "??" or missing parentheses. To fix a dependency, set it manually with PowerShell:

Get-ClusterResource "MyResource" | Set-ClusterResourceDependency -Dependency "[ResourceName]"

Registry Corruption in Cluster Database

In rare cases, the cluster database in the registry gets a corrupt string. This usually happens after a failed update or a hard crash. To check the registry:

1. Open Regedit on a cluster node.
2. Navigate to HKLM\Cluster\Resources.
3. Expand each GUID key and look at the Name and Dependencies values. They should match what you see in Failover Cluster Manager. If you see garbage data, you can export the good resource's name from another node and import it. But honestly, if it's this deep, you may need to restore the cluster quorum.

Third-Party Cluster Extensions

Some storage vendors install their own resource DLLs that use non-standard string formats. I once had a Dell EqualLogic SAN integration that injected a colon into a resource name. Uninstalling the vendor extension, cleaning up the resource, and reinstalling fixed it.

Prevention

You can stop this from happening again. Here's what I tell every client:

• Standardize naming conventions. Use only letters, numbers, hyphens, and underscores. No spaces if you can avoid it – use CamelCase or hyphens instead. Example: FileServer-Corp-Data instead of File Server (Corp Data).
• Never edit cluster resources from anything but Failover Cluster Manager or PowerShell. No direct registry edits, no ADSI Edit, no third-party tools that write to cluster objects.
• Set up a scheduled task to run a lightweight validation once a week. Use this script:
  

  Get-ClusterResource | ForEach-Object { if ($_.Name -match '[^a-zA-Z0-9\-_\. ]') { Write-Warning "Bad char in resource: $($_.Name)" } }

  This catches any weird characters before they cause an outage.
• Keep your cluster OS updated. Microsoft fixed a few parsing edge cases in Server 2022 cumulative updates. If you're on Server 2016, apply the latest updates.

I've seen this error knock a 50-node cluster sideways for a day. Now you know how to squash it in 10 minutes flat.