Upgrade StorageEPUB linked file not loading in internal reader — NetworkError (macOS, ZotMoov)
I'm unable to open EPUB files in Zotero's internal reader when they are stored as linked files (via ZotMoov) on iCloud Drive. The reader tab opens but displays a blank white screen.
**Environment**
- Zotero 9.0.1 (ARM64)
- macOS 15.7.4 (Sequoia)
- MacBook Pro M3 Pro
- ZotMoov 1.2.28
- EPUB stored as linked file in: ~/Library/Mobile Documents/com~apple~CloudDocs/Zotero Library/
- File is fully downloaded locally (not an iCloud placeholder)
Debug ID: D2120913777
**What happens**
The log shows repeated errors:
```
ReaderTab "[title]": TypeError: NetworkError when attempting to fetch resource.
```
Zotero correctly identifies the file as application/epub+zip and attempts to open it in the internal reader, but the fetch fails. The file is physically present on disk.
**What works**
- Same EPUB opens fine in external readers (Calibre, etc.)
- PDF linked files open correctly in Zotero's internal reader
- EPUB stored files (in Zotero storage) open correctly
**Root cause hypothesis**
The internal EPUB reader appears to use a network fetch mechanism that fails when the file path resolves outside of Zotero's storage directory (e.g. iCloud Drive path). PDF linked files seem to handle this differently.
**Workflow context**
I use ZotMoov to store files in iCloud so my Kobo e-reader can access them. Disabling ZotMoov or copying EPUBs into Zotero storage fixes the issue but breaks the e-reader workflow.
**Environment**
- Zotero 9.0.1 (ARM64)
- macOS 15.7.4 (Sequoia)
- MacBook Pro M3 Pro
- ZotMoov 1.2.28
- EPUB stored as linked file in: ~/Library/Mobile Documents/com~apple~CloudDocs/Zotero Library/
- File is fully downloaded locally (not an iCloud placeholder)
Debug ID: D2120913777
**What happens**
The log shows repeated errors:
```
ReaderTab "[title]": TypeError: NetworkError when attempting to fetch resource.
```
Zotero correctly identifies the file as application/epub+zip and attempts to open it in the internal reader, but the fetch fails. The file is physically present on disk.
**What works**
- Same EPUB opens fine in external readers (Calibre, etc.)
- PDF linked files open correctly in Zotero's internal reader
- EPUB stored files (in Zotero storage) open correctly
**Root cause hypothesis**
The internal EPUB reader appears to use a network fetch mechanism that fails when the file path resolves outside of Zotero's storage directory (e.g. iCloud Drive path). PDF linked files seem to handle this differently.
**Workflow context**
I use ZotMoov to store files in iCloud so my Kobo e-reader can access them. Disabling ZotMoov or copying EPUBs into Zotero storage fixes the issue but breaks the e-reader workflow.
If so, sounds like this is a ZotMoov issue, and you'll need to report it to that plugin's developer.
So if you were to test a linked epub file on a local drive on your system, and that worked, then it would point more clearly towards something about iCloud (and Zotero's interaction with it) being the issue.
But you do say that "Disabling ZotMoov or copying EPUBs into Zotero storage fixes the issue". To clarify, what Zotmoov operation are you then *not* doing that fixes/avoids the issue ? Or does *only* disabling Zotmoov fix the issue by itself ? (which seems the least likely ... since once a file is linked, Zotmoov no longer has any involvement in Zotero's interactions with the linked file, AFAIK).
A problem that *doesn't* involve a plugin obviously appears less complex, and also more obviously within the Zotero devs' purview. So you could also test an epub file attachment on iCloud that is instead linked via Zotero's right-click Add Attachment\Linked File ... which would then allow you to say that the iCloud problem still occurs when Zotmoov is not part of the equation at all ... if it does.
I tested both scenarios:
A) Disabled ZotMoov entirely, linked the EPUB directly via Zotero's "Add Linked File" from iCloud folder → blank screen, same NetworkError
B) copied the EPUB to ~/Downloads (fully local, no iCloud), imported as stored file → blank screen, same NetworkError
The file opens correctly in Apple Books tho. When converted to PDF via Calibre, the PDF opens fine in Zotero's reader.
This rules out both ZotMoov and iCloud as causes. Would Tthe issue appears specificly to Zotero's EPUB reader on this system (Zotero 9.0.1 ARM64, macOS 15.7.4 Sequoia, M3 Pro) ? Happy to run any further tests if that helps.
Opening the EPUB in Calibre and using "Save a copy" produces a clean enough file that Zotero's reader accepts. The fix works consistently across multiple affected files.
Hope this helps someone else down the line!
I'll send the OPF to @support.
Thank you for your help !