License parsing error and performance issue during DOC/DOCX to PDF conversion on Linux (Java 8)

Hi Team,

We are currently using GroupDocs.Conversion for Java to support a functionality where files in non-PDF formats
(.doc, .docx, .xls, .xlsx) are converted to PDF, and later all PDFs are merged into a single document.

Environment details

OS: Linux

Java version: Java 8

GroupDocs version: 23.6

Issue 1: License parsing error during conversion initialization

While running the application in the dev environment, we are encountering the following exception during conversion:

com.groupdocs.conversion.legacy.exceptions.GroupDocsException:
class com.groupdocs.conversion.internal.c.a.s.exceptions.G: License parsing error
—> java.lang.IllegalArgumentException:
Property 'http://javax.xml.XMLConstants/property/accessExternalDTD’ is not recognized.

Relevant stack trace snippet:

com.groupdocs.conversion.legacy.exceptions.GroupDocsException: class com.groupdocs.conversion.internal.c.a.s.exceptions.G: License parsing error —> java.lang.IllegalArgumentException: Property 'http://javax.xml.XMLConstants/property/accessExternalDTD’ is not recognized.
— End of inner exception stack trace —
com.groupdocs.conversion.internal.c.a.s.internal.oh.v.a(Unknown Source)
com.groupdocs.conversion.internal.c.a.s.internal.oh.Z.ex(Unknown Source)
com.groupdocs.conversion.internal.c.a.s.internal.oh.Z.ez(Unknown Source)
com.groupdocs.conversion.internal.c.a.s.License.setLicense(Unknown Source)
com.groupdocs.conversion.internal.c.g.f.l.aspose.a.Ex(Unknown Source)
com.groupdocs.conversion.internal.c.g.f.l.aspose.a.L(Unknown Source)
com.groupdocs.conversion.internal.c.g.f.common.d.zyp(Unknown Source)
com.groupdocs.conversion.Converter.init(Unknown Source)
com.groupdocs.conversion.Converter.(Unknown Source)
com.groupdocs.conversion.Converter.(Unknown Source)
org.mit.compliance.attachmentexport.util.AttachmentExportUtil.convertToPdfIfRequired(AttachmentExportUtil.java:78)

This exception occurs when executing the following line of code:

try (Converter converter = new Converter(originalFilePath)) {
PdfConvertOptions options = new PdfConvertOptions();
}

It appears that the exception is thrown during the initialization of the Converter, before the actual conversion starts.

Previously, we were using GroupDocs version 25.9.
With this version, the conversion process did not complete successfully - the execution appeared to hang when conversion started, and the flow did not proceed further.

Due to this, we downgraded to version 23.6, but are now facing the license parsing issue mentioned above.

Issue 2: Performance concern with large DOC files

Additionally, we observed a performance issue while converting large DOC files:

File size: 40–50 MB

Content: Plain Text

Conversion time: around 23 minutes

We would like to understand:

Whether this conversion time is expected

If there are recommended configurations, JVM options, or GroupDocs settings to improve performance for large documents

Requesting for support on below queries:

  1. Understanding the root cause of the license parsing error in Java 8 / Linux environment and recommended fix.

  2. Guidance on performance optimization for large DOC/DOCX to PDF conversions

Thank you for your support.

@suchithrapv

Hello,

Thank you for reaching out and providing detailed information about the issues you are experiencing.

Your request has been received and will be reviewed by the appropriate team. We will get back to you as soon as possible with further assistance.


If you have any additional details or files (e.g., a minimal reproducible example, license file, or stack‑trace) that you can share, please attach them to your post. This will help us investigate the problem more efficiently.


Kind regards,
Support Team


This response is based on the information you provided. If you have any further questions or need to add more context, feel free to reply to this thread.