# Collabora office, what means log error : CALLBACK\_ERROR in zipapi

**URL:** <https://forum.collaboraonline.com/t/collabora-office-what-means-log-error-callback-error-in-zipapi/4800>\
**Category:** User Support\
**Created:** [June 24, 2026, 12:02pm UTC](https://forum.collaboraonline.com/t/collabora-office-what-means-log-error-callback-error-in-zipapi/4800 "2026-06-24T12:02:01Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![adhfr](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.collaboraonline.com/adhfr/32/2311_2.png) [@adhfr](https://forum.collaboraonline.com/u/adhfr)\
**Post date:** [June 24, 2026, 12:02pm UTC](https://forum.collaboraonline.com/t/collabora-office-what-means-log-error-callback-error-in-zipapi/4800/1 "2026-06-24T12:02:01Z")

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What does mean log error :

```auto
vm-colla-01-prod docker/collabora-app-1[19602]: kit-668563-669353 2026-02-12 10:29:25.897299 +0000 [kitbgsv_1dee_003] ERR ToMaster-1a790: CALLBACK_ERROR: {
vm-colla-01-prod docker/collabora-app-1[19602]: "code": "0x20d(Error Area:Io Class:General Code:13) arg1=The stream seems to be broken! at \/opt\/collaboraoffice\/debugsource\/package\/source\/zipapi\/XUnbufferedStream.cxx:302",
vm-colla-01-prod docker/collabora-app-1[19602]: "kind": "",
vm-colla-01-prod docker/collabora-app-1[19602]: "cmd": "",
vm-colla-01-prod docker/collabora-app-1[19602]: "message": "Erreur générale.\nGeneral input\/output error."

```

---

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**Author:** ![darshan](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.collaboraonline.com/darshan/32/2230_2.png) [@darshan](https://forum.collaboraonline.com/u/darshan)\
**Post date:** [June 26, 2026, 5:50am UTC](https://forum.collaboraonline.com/t/collabora-office-what-means-log-error-callback-error-in-zipapi/4800/2 "2026-06-26T05:50:42Z")

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hi @adhfr

Welcome to collabora online forum

> [@adhfr](#):
>
> What does mean log error :
> 
> ```auto
> vm-colla-01-prod docker/collabora-app-1[19602]: kit-668563-669353 2026-02-12 10:29:25.897299 +0000 [kitbgsv_1dee_003] ERR ToMaster-1a790: CALLBACK_ERROR: {
> vm-colla-01-prod docker/collabora-app-1[19602]: "code": "0x20d(Error Area:Io Class:General Code:13) arg1=The stream seems to be broken! at \/opt\/collaboraoffice\/debugsource\/package\/source\/zipapi\/XUnbufferedStream.cxx:302",
> vm-colla-01-prod docker/collabora-app-1[19602]: "kind": "",
> vm-colla-01-prod docker/collabora-app-1[19602]: "cmd": "",
> vm-colla-01-prod docker/collabora-app-1[19602]: "message": "Erreur générale.\nGeneral input\/output error."
> 
> ```

**Collabora tried to open or save a document and the document’s ZIP stream was incomplete or corrupt** — the file content it received didn’t match the file’s own internal structure.

If you can share the log lines immediately before this `CALLBACK_ERROR` (the WOPI request/transfer entries for the same session), I can help pin down whether it’s a broken transfer or an actually corrupt document.

This is a sensitive topic only in the sense of data integrity — if it turns out to be a corrupt file, the user may have lost recent edits, so it’s worth checking whether a prior good version exists in the storage backend’s version history.

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**Author:** ![adhfr](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.collaboraonline.com/adhfr/32/2311_2.png) [@adhfr](https://forum.collaboraonline.com/u/adhfr)\
**Post date:** [July 15, 2026, 7:02am UTC](https://forum.collaboraonline.com/t/collabora-office-what-means-log-error-callback-error-in-zipapi/4800/3 "2026-07-15T07:02:33Z")

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Thank Darshan ,

Previous errors I can see :

2026-02-12T11:29:24.704131+01:00 nov-11-vm-colla-01-prod docker/collabora-app-1[19602]: sh: 1: /usr/bin/coolmount: Operation not permitted  
2026-02-12T11:29:24.704850+01:00 nov-11-vm-colla-01-prod docker/collabora-app-1[19602]: sh: 1: /usr/bin/coolmount: Operation not permitted  
2026-02-12T11:29:24.705890+01:00 nov-11-vm-colla-01-prod docker/collabora-app-1[19602]: sh: 1: /usr/bin/coolmount: Operation not permitted  
2026-02-12T11:29:25.120422+01:00 nov-11-vm-colla-01-prod docker/collabora-app-1[19602]: kit-664371-664371 2026-02-12 10:29:25.120109 +0000 [kitbroker\_1db9] WRN #26: Background save process disconnected but not terminated 669340| kit/KitWebSocket.cpp:339

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<div class="post-metadata">

**Author:** ![darshan](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.collaboraonline.com/darshan/32/2230_2.png) [@darshan](https://forum.collaboraonline.com/u/darshan)\
**Post date:** [July 15, 2026, 7:14am UTC](https://forum.collaboraonline.com/t/collabora-office-what-means-log-error-callback-error-in-zipapi/4800/4 "2026-07-15T07:14:16Z")

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hi @adhfr 👋

Those lines are the root cause: `coolmount: Operation not permitted` means your Docker container can’t perform mount operations. That kills the background save process mid-write, so the document stream comes out truncated — which is exactly what the zipapi “stream seems to be broken” error is complaining about. Your files in storage are most likely fine.

Fix: run the container with `--cap-add MKNOD --cap-add SYS_ADMIN` (compose: `cap_add: [MKNOD, SYS_ADMIN]`). If you’re on rootless Docker or a NAS where mounts aren’t possible, add `-e "extra_params=--o:mount_jail_tree=false"` instead.