dotnet/wpf · error · ArgumentException

The given data space label name is already in use.

Error message

The given data space label name is already in use.

What it means

DataSpaceManager.DefineDataSpace throws ArgumentException (SR.DataSpaceLabelInUse) when the newDataSpaceLabel already names a defined data space. Labels are unique per compound file; defining a duplicate is rejected.

Solutions

1. Check DataSpaceIsDefined(label) before calling DefineDataSpace and skip/reuse if it exists.
2. Choose a unique label (append a counter or timestamp) when creating multiple data spaces.
3. Use a fresh compound file if the old label must be redefined with a different transform stack.

Example fix

// before
manager.DefineDataSpace(stack, "EncryptedData"); // throws on second run
// after
if (!manager.DataSpaceIsDefined("EncryptedData"))
    manager.DefineDataSpace(stack, "EncryptedData");

if (manager.DataSpaceIsDefined(label)) { /* skip define or pick a new label */ }

try { manager.DefineDataSpace(stack, label); } catch (ArgumentException) { label = label + Guid.NewGuid().ToString("N"); manager.DefineDataSpace(stack, label); }

When it happens

Trigger: Calling DefineDataSpace(stack, label) where DataSpaceIsDefined(label) is true — i.e. the label was defined earlier in the same compound file session.

Common situations: Re-running an initialization routine against an existing compound file, or retrying code after a partial failure where the first define already succeeded.

Understand the failure class

Background: "already exists" / EEXIST / FileAlreadyExistsException: what the 'file already exists' error means and how to fix it — this error's family across 37 libraries.

Related errors

• SR.TransformStackValid
• Can only countersign parts with Digital Signature…
• Duplicates not allowed - signature part already exists.
• Must specify an item to sign.
• Parameter cannot be a zero-length string.

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/1754b5b1003c6c3a. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/WindowsBase/System/IO/Packaging/CompoundFile/DataSpaceManager.cs:589

    /// <param name="newDataSpaceLabel">New data space label</param>
    internal void DefineDataSpace( string[] transformStack, string newDataSpaceLabel )
    {
        CheckDisposedStatus();
        // Data space must have at least one transform
        if( null == transformStack ||
            0 == transformStack.Length )
            throw new ArgumentException(
                SR.TransformStackValid);

        // Given label must be a non-empty string
        CU.CheckStringAgainstNullAndEmpty(newDataSpaceLabel, "newDataSpaceLabel");

        // Given label must not be a reserved string
        CU.CheckStringAgainstReservedName(newDataSpaceLabel, "newDataSpaceLabel");

        // Given label must not already be in use
        if( DataSpaceIsDefined( newDataSpaceLabel ) )
            throw new ArgumentException(
                SR.DataSpaceLabelInUse);

        // Given transform array must include labels that have already been defined
        foreach( string transformLabel in transformStack )
        {
            CU.CheckStringAgainstNullAndEmpty( transformLabel, "Transform label" );

            if( !TransformLabelIsDefined( transformLabel ) )
                throw new ArgumentException(
                    SR.TransformLabelUndefined);
        }

        // Passes all inspection, data space definition successful.
        SetDataSpaceDefinition( newDataSpaceLabel, new DataSpaceDefinition(new ArrayList(transformStack), null));
        _dirtyFlag = true;

        return;
    }

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