Bug: Local sync - Failed to decode knowledge list response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge

[carlosomarpabon]

When I run the local file sync service I the the error:

Failed to decode knowledge list response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge

It then proceeds to act as if many of the files are duplicates. Am I correct in thinking that instead, it should find the files, see if they have changed, and move on? I fear that this issue will prevent syncing files when they are updated and only upload new files.

Note that all knowledge bases were made fresh, brand new empty folders for the tool to populate. The following are the logs after running it a second time (files uploaded the first time).

root@openwebui-content-sync:~# docker logs openwebui-content-sync
Loading configuration from: config.yaml
Default OpenWebUI BaseURL: http://192.168.2.117:8080
Confluence API Key loaded: NOT SET
Config file exists, loading from: config.yaml
After loading config file - OpenWebUI BaseURL:
Final OpenWebUI BaseURL: http://192.168.2.117:8080
Environment OPENWEBUI_BASE_URL: http://192.168.2.117:8080
Final Confluence API Key: NOT SET
Environment CONFLUENCE_API_KEY: NOT SET
time="2026-01-16T19:07:45Z" level=info msg="Starting OpenWebUI Content Sync"
time="2026-01-16T19:07:45Z" level=info msg="Using mapping-based knowledge ID assignment - files will use their individual knowledge IDs from mappings"
time="2026-01-16T19:07:45Z" level=info msg="Initializing file index from OpenWebUI..."
time="2026-01-16T19:07:45Z" level=info msg="Starting scheduler with interval: 15m0s"
time="2026-01-16T19:07:45Z" level=info msg="Initializing file index from OpenWebUI knowledge bases..."
time="2026-01-16T19:07:45Z" level=error msg="Failed to decode knowledge list response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge"
time="2026-01-16T19:07:45Z" level=warning msg="Failed to get files from knowledge source fedfbe3f-a5a6-4cd2-af0b-6168c4eadc0e: failed to decode response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge"
time="2026-01-16T19:07:45Z" level=error msg="Failed to decode knowledge list response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge"
time="2026-01-16T19:07:45Z" level=warning msg="Failed to get files from knowledge source 43ab5f6e-c9ae-4e49-8a75-2f9b24b2d775: failed to decode response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge"
time="2026-01-16T19:07:45Z" level=info msg="File index now contains 65 files from 2 knowledge bases"
time="2026-01-16T19:07:45Z" level=info msg="Running initial sync..."
time="2026-01-16T19:07:45Z" level=info msg="Starting file synchronization"
time="2026-01-16T19:07:45Z" level=warning msg="Failed to list knowledge sources: failed to decode response: json: cannot unmarshal object into Go value of type []*openwebui.Knowledge"
time="2026-01-16T19:07:45Z" level=info msg="Syncing files from adapter: local"
time="2026-01-16T19:07:49Z" level=info msg="File 89296db6-3770-49e6-8a35-b4875d22d807 processing completed after 4s"
time="2026-01-16T19:07:49Z" level=error msg="Add file to knowledge failed with status 400: {"detail":"400: Collection expecting embedding with dimension of 1024, got 768"}"
time="2026-01-16T19:07:49Z" level=error msg="Failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: Collection expecting embedding with dimension of 1024, got 768"}"
time="2026-01-16T19:07:49Z" level=error msg="Failed to sync file Syncthing.md: failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: Collection expecting embedding with dimension of 1024, got 768"}"
time="2026-01-16T19:07:57Z" level=info msg="File 6c7ef86c-eb0f-49d6-95dd-a86357cc6568 processing completed after 8s"
time="2026-01-16T19:07:57Z" level=error msg="Add file to knowledge failed with status 400: {"detail":"400: Duplicate content detected. Please provide unique content to proceed."}"
time="2026-01-16T19:07:57Z" level=error msg="Failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: Duplicate content detected. Please provide unique content to proceed."}"
time="2026-01-16T19:07:57Z" level=error msg="Failed to sync file BigO_Cheatsheet_Zero_To_Mastery_V1.01.pdf: failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: Duplicate content detected. Please provide unique content to proceed."}"
time="2026-01-16T19:08:01Z" level=info msg="File 85686936-cc2f-4057-9196-41d90883adab processing completed after 4s"
time="2026-01-16T19:08:01Z" level=error msg="Add file to knowledge failed with status 400: {"detail":"400: Duplicate content detected. Please provide unique content to proceed."}"
time="2026-01-16T19:08:01Z" level=error msg="Failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: Duplicate content detected. Please provide unique content to proceed."}"
time="2026-01-16T19:08:01Z" level=error msg="Failed to sync file Prim Pay Bonus.md: failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: Duplicate content detected. Please provide unique content to proceed."}"
time="2026-01-16T19:10:07Z" level=warning msg="File processing wait failed: file processing failed with status: failed after 2m6s, continuing anyway"
time="2026-01-16T19:10:07Z" level=error msg="Add file to knowledge failed with status 400: {"detail":"400: The content provided is empty. Please ensure that there is text or data present before proceeding."}"
time="2026-01-16T19:10:07Z" level=error msg="Failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: The content provided is empty. Please ensure that there is text or data present before proceeding."}"
time="2026-01-16T19:10:07Z" level=error msg="Failed to sync file Principal Benefits/2026/AccountBasedHealthPlan.pdf: failed to add file to knowledge: add file to knowledge failed with status 400: {"detail":"400: The content provided is empty. Please ensure that there is text or data present before proceeding."}"

[carlosomarpabon]

EDIT: Removing code tags made the logs a little easier to read.

[meganoob1337]

Can you try adding a file via API without the tool? This sounds like it might be an error on OWUIs side. You could try to reproduce it with an older version?

[carlosomarpabon]

I tested uploading a file directly via the OpenWebUI API as suggested by @meganoob1337. The direct API calls work without issues:

1. File upload (POST /api/v1/files/) - Success
2. Add to knowledge base (POST /api/v1/knowledge/{id}/file/add) - Success

However, when I tested the knowledge list endpoint (GET /api/v1/knowledge/), I found the root cause:

The API now returns a paginated object instead of a direct array:

{
"items": [{...}, {...}, {...}],
"total": 3
}

The sync tool expects []*openwebui.Knowledge (a direct array), but receives an object with items and total fields, causing:
json: cannot unmarshal object into Go value of type []*openwebui.Knowledge

This change was introduced in OpenWebUI v0.6.42, which rebuilt knowledge base file management with pagination support. The release notes state: "GET /knowledge/{id}/files endpoint now returns paginated results... requiring updates to custom integrations."

The fix would require updating the tool's response parsing to handle the new paginated format, something like:

type KnowledgeListResponse struct {
Items []*Knowledge json:"items"
Total int json:"total"
}

[berturion]

Hi. I am facing the same problem. It is not that hard to fix I think. My collection can't be updated anymore. Thanks.

[Ranktotop]

Same here. How did you resolved the issue?