Handle PDF/A normalization errors using AllowedErrors parameter
Certain actions may alter the visual appearance of the file or remove crucial data at the time of conversion. You must identify conversion errors that are tolerable and can be allowed, and the ones which are critical and should not be allowed.
To not include errors that are critical for your processing, set the value of AllowedErrors parameter appropriately.
You can do the following to minimize the document conversion errors:
Convert input documents to PDF/A-2 instead of PDF/A-1. As PDF/A-2 allows some features of newer versions of the PDF reference such as transparency, optional content (layers), or embedded files.
If fonts were substituted for earlier processing, install the missing fonts.
For documents with non-convertible XMP Metadata, update the PDF creating software to generate valid XMP metadata.