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MSB4248 diagnostic code

  • Članak

This article describes the MSB4248 error code.

Message text

MSB4248: Cannot expand metadata in expression 'expression'.

Remarks

The MSB4248 error occurs when MSBuild is unable to expand item metadata in a build operation. This situation typically happens when metadata references are used in an invalid context or when the metadata being referenced doesn't exist for the item.

Possible causes

This error can be raised for the following reasons:

  1. Metadata not supported for the item For example, referencing %(RootDir) on an item that isn't a path.

  2. Dynamic item metadata in complex builds

    • Dynamically generated item metadata may not always be available, depending on the build configuration.

Resolution

  1. Validate that the requested metadata is consistent with the item.

  2. Conditionally access metadata

    • For dynamic builds, ensure metadata is accessed conditionally to avoid referencing undefined metadata:

      <Message Text="Target Framework: %(Metadataname)" Condition="'%(Metadataname)' != ''" />

Applies to

All versions of MSBuild