[EN] A 'UseCMap' entry in a CMap does not match the 'UseCMap' entry in CMap stream

Description

The encoding of characters is inconsistent between the CMap and the CMap stream.

In a PDF file, a CMap (Character Map) is used to map character codes to glyphs. The UseCMap entry is used to refer to another CMap embedded in a CMap stream. If the UseCMap entry in the CMap and the associated CMap stream do not match, this error occurs. This can lead to incorrect display or interpretation of text content, as the CMap cannot be resolved correctly.

Common Causes

• Different UseCMap entries in different parts of the PDF: The CMap definition itself and the CMap stream refer to different CMaps, leading to inconsistencies.
• Damage to the PDF structure: If parts of the PDF file are damaged, the UseCMap entry may have been incorrectly assigned or partially deleted.
• Errors when creating or editing the PDF: The PDF may have been created with incompatible or non-standard-compliant tools that generate incorrect CMap references.
• Outdated or incompatible CMaps: If an outdated CMap or an incompatible version of UseCMap is used, these references may not be merged correctly.

Suggested Solutions

• Verification with Preflight Tools: Open the PDF in Adobe Acrobat Pro and use the Preflight Tool: Go to Tools > Print Production > Preflight. Perform a check to ensure that all CMap references and their consistency are checked. Preflight can automatically fix some issues.
• Use standards-compliant PDF software: Make sure you use PDF software that adheres to the PDF standard, such as Adobe InDesign, to avoid errors in CMap integration.

You can find a help article here:

Overview – Error In Page Description