Group Library PDFs Open as Black Screen (Web + Desktop), Only One File Opens Normally

sreeram.ramakrishnan
Hello everyone,

We are facing a serious issue with a Zotero group library and would really appreciate some guidance.

Problem description:
Almost all PDFs in our group library open as a completely black screen.
This happens both in:

Zotero Desktop, and

Zotero Web.

However, one PDF in the group opens correctly everywhere, and all PDFs in personal libraries open normally.

This problem affects multiple users in the same group.
https://s3.amazonaws.com/zotero.org/images/forums/u14731110/4fnfitab4b0ncf8gjf1g.png
On the Zotero website, one file opens correctly, but almost all other group PDFs still show a black screen. This strongly suggests a server-side corruption of the group attachment metadata, not a local client issue.

At the moment, this problem is blocking access to our shared research materials for the entire group.

Has anyone experienced something similar, or is there a way for Zotero staff to repair the corrupted group attachments on the server?

Thank you very much for your help.
  • dstillman Zotero Team
    Can you provide a Debug ID for trying to open a PDF?
  • sreeram.ramakrishnan
    D1991491897
  • dstillman Zotero Team
    [JavaScript Error: "InvalidPDFException: Worker 'import' failed: {"existingAnnotations":[],"error":"{\"message\":\"The PDF file is empty, i.e. its size is zero bytes.\",\"name\":\"InvalidPDFException\"}"}" {file: "chrome://zotero/content/xpcom/pdfWorker/manager.js" line: 324}]
    You have lots of empty (zero-byte) files in the library, all uploaded around November 3–4, 2025. Files added before then and after then are mostly fine (except for a few files added in June 2025), so it's not all files. About 1/3 of the files in the library are empty.

    I don't think we've ever seen anything like this, and the files in question seem to have been added by various people in the group, so I would guess this is due to shared security software on your computers. This is also affecting webpage snapshots, which are zipped before they're uploaded, and in your case are valid zips of empty .html files, so it would have to have been something happening locally, not a server-side problem.

    Individual members can right-click → Show File on a file they added, on the computer where they added it, to see if their local copy is zero bytes. E.g., you can paste some of these into the search bar in All Fields & Tags mode to see some of the files that you added that are empty online:

    9J5MQSL5
    G97IXLS5
    NHC87N22
    SRWIRH96
    VNLRHMV3
    Z48ALL74
  • sreeram.ramakrishnan
    edited today at 9:28am
    Hello Mr. Dstillman,

    Thank you very much for investigating this issue and for the detailed explanation.

    From our side, we would like to clarify the current situation and ask for guidance on how to proceed without losing existing data.

    At the moment, three group members are affected by this issue and are unable to open many files in the group library:

    sreeram.ramakrishnan@mailbox.tu-dresden.de

    martin.baumgarten@tu-dresden.de - Debug Id: D243653756

    johannes.koal@tu-dresden.de

    However, one group member (tony.richter1@tu-dresden.de - Debug Id: D1157004639) is able to access and open all files in the group library normally, without seeing the black screen or empty-file behavior.

    This group library contains very old material, including contributions from former students, and—most importantly—a large number of notes, highlights, and annotations that we need to retain. Because of this, we are very concerned about taking any action that might overwrite or delete existing notes or markings stored on the Zotero servers.

    Could you please advise us on:

    The safest way to resolve or repair the empty (zero-byte) files in the group library

    Whether it is possible to restore or reattach the correct PDFs without affecting existing notes and annotations

    Whether one unaffected group member (who can still access all files) could be used as a reference source for recovery

    Preserving the historical notes and annotations is extremely important for our ongoing research, so we would appreciate guidance on the best workflow to handle this safely.

    Thank you again for your time and support.

    Kind regards,
    Sreeram Ramakrishnan
  • sreeram.ramakrishnan
    edited today at 9:29am
    Hello Mr. Dstillman,

    I would like to provide a correction and an update to my previous message.

    Earlier, I mentioned that one group member (tony.richter1@tu-dresden.de) was able to open all files in the group library. However, after updating Zotero to the latest version and performing a full resynchronization, he is now also unable to open the affected PDFs and sees the same black screen / empty-file behavior as the rest of us.

    This means that all tested group members are now affected, and no one can currently open the majority of the PDFs in the group library.

    We have also generated a Debug ID from attempting to open one of the affected group PDFs on his system after the update and resync:

    Debug ID: D451320095

    We wanted to clarify this as soon as possible, since it may be relevant for diagnosing whether the issue is related to how newer Zotero versions handle these zero-byte attachments.

    Please let us know how best to proceed, especially with regard to safely restoring the files while preserving the existing notes and annotations, which are very important for our ongoing research.

    Thank you again for your continued help.

    Kind regards,
    Sreeram Ramakrishnan
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