What to do about "Failed to set metadata for the PDF format" on export?

[halloleo]

Hi!

I regularly export the books in my library with embedded metadata (via calibredb export) so that other tools can see/index them.

Now I get the following error:

Failed to set metadata for the PDF format of: Owner's Manual – HS11/HS33
Traceback (most recent call last):
  File "calibre/utils/podofo/__init__.py", line 38, in set_metadata
  File "calibre/utils/ipc/simple_worker.py", line 256, in fork_job
  File "calibre/utils/ipc/simple_worker.py", line 181, in run_job
  File "calibre/utils/ipc/simple_worker.py", line 120, in communicate
calibre.utils.ipc.simple_worker.WorkerError: Worker failed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "calibre/customize/ui.py", line 447, in set_file_type_metadata
  File "calibre/customize/builtins.py", line 544, in set_metadata
  File "calibre/ebooks/metadata/pdf.py", line 187, in set_metadata
  File "calibre/utils/podofo/__init__.py", line 42, in set_metadata
Exception: Failed to set PDF metadata in (Owner's Manual – HS11/HS33): Traceback (most recent call last):
  File "calibre/utils/ipc/simple_worker.py", line 304, in main
  File "calibre/utils/podofo/__init__.py", line 99, in set_metadata_
podofo.Error: An internal error occurred.
File: /private/var/folders/hb/2_22y10x72j2tltq8b0ygzp80000gn/T/t/podofo-avye7kfp/src/base/PdfParser.cpp Line: 272 Unable to load objects from file.
File: /private/var/folders/hb/2_22y10x72j2tltq8b0ygzp80000gn/T/t/podofo-avye7kfp/src/base/PdfParserObject.cpp Line: 403 Unable to parse the stream for object 867 0 obj .
File: /private/var/folders/hb/2_22y10x72j2tltq8b0ygzp80000gn/T/t/podofo-avye7kfp/src/base/PdfEncrypt.cpp Line: 411 Error AES-decryption data

How can I fix this? It looks like that one particular book ("Owner's Manual – HS11_HS33.pdf") has some encryption set, but I can view the file without any password, so I don't understand why calibe has problems setting metadata.

[kovidgoyal]

There's nothing to do. PODOFO cant handle that PDF. You could report it to them, but most likely the PDF file is broken in some way that makes editing it fail while simply viewing doesnt.

[DNSB]

Look at the properties of the files (I used Acrobat Reader). I've attached an image of the security settings for a document that has password protected modification settings but allow opening/printing without a password.

[halloleo]

Originally Posted by kovidgoyal

There's nothing to do. PODOFO cant handle that PDF. You could report it to them, but most likely the PDF file is broken in some way that makes editing it fail while simply viewing doesnt.

Thanks for replying, but I don't think the PDF is broken. I reckon the problem is that the PDF does - as @DNSB pointed out - not allow to be modified.

[halloleo]

Originally Posted by DNSB

Look at the properties of the files.

Good point! That was indeed the problem: The PDF was not allowed to be modified. I fixed the write-permission issue by copying the content via the `qpdf` command line program:

qpdf --empty --pages <original.pdf> -- writable.pdf

Then I copied writable.pdf into the calibre database.

This is certainly not perfect, because I loose possible metadata from the original PDF, but at least I can export the PDF with the metadata from calibre.

[DNSB]

Originally Posted by halloleo

Good point! That was indeed the problem: The PDF was not allowed to be modified. I fixed the write-permission issue by copying the content via the `qpdf` command line program:

qpdf --empty --pages <original.pdf> -- writable.pdf

Then I copied writable.pdf into the calibre database.

This is certainly not perfect, because I loose possible metadata from the original PDF, but at least I can export the PDF with the metadata from calibre.

Good to hear that you found a workaround.