Error while exporting opf metadata into pdf file

[liametoh]

Hi, I want to export the metadata into de opf file to the pdf associated.

The problem is when I tried this get the following error:

calibre, version 2.75.1
WARNING: Error while saving: Failed to update metadata in some books, click "Show details" for more information

Failed to update the metadata in the PDF format of: Understanding Analysis, 2ndEd by Abbott, Stephen, with error:
    Traceback (most recent call last):
      File "/usr/lib/calibre/calibre/customize/ui.py", line 438, in set_file_type_metadata
        plugin.set_metadata(stream, mi, ftype.lower().strip())
      File "/usr/lib/calibre/calibre/customize/builtins.py", line 541, in set_metadata
        set_metadata(stream, mi)
      File "/usr/lib/calibre/calibre/ebooks/metadata/pdf.py", line 175, in set_metadata
        return podofo_set_metadata(stream, mi)
      File "/usr/lib/calibre/calibre/utils/podofo/__init__.py", line 44, in set_metadata
        raise Exception('Failed to set PDF metadata in (%s): %s'%(mi.title, e.orig_tb))
    Exception: Failed to set PDF metadata in (Understanding Analysis, 2ndEd): Traceback (most recent call last):
      File "/usr/lib/calibre/calibre/utils/ipc/simple_worker.py", line 286, in main
        res = {'result':func(*args, **kwargs)}
      File "/usr/lib/calibre/calibre/utils/podofo/__init__.py", line 61, in set_metadata_
        p.open(u'input.pdf')
    Error: A object was expected but not found.

The same happens when trying to export to a disk the file and calibre try to export the metadata.opf to the pdf.

[kovidgoyal]

Your version of calibre is ancient, update. Although that error indicates a malformed PDF file.