Environment

• Server version: 7.1.7
• Node.js version: v24.2.0
• npm version: 11.3.0

Description

A PUT request completely deletes file contents on server side before all data has been successfully processed. This can lead to a complete data loss of the respective file on slow / unreliable internet connections.

To reproduce:

1. setup a local CSS server and setup a pod with a markdown document, e.g. /alice/markdown.md
2. write some content to this document
3. use browser dev tools to throttle internet. I tested with these settings in chrome:

• Download 5 kbit/s
• Upload 3 kbit/s
• Latency 300ms
• Packet loss 5%
• Packet length queue 3

2. make a PUT request to write new content to the file, e.g.

fetch("http://localhost:3000/alice/markdown.md", {
  "headers": {
    "content-type": "text/markdown",
  },
  "body": "some markdown content, propably not too short to have some data to process",
  "method": "PUT"
});

Actual behaviour:

• As soon as the PUT request reaches the server the markdown file is completely cleared from existing content
• The fetch is still pending due to the bad connection
• server responds with status 500
• new file content is not saved, the old content is lost

Logs from CSS:

2025-10-22T15:29:33.396Z [HandlerServerConfigurator] {Primary} info: Received PUT request for /alice/markdown.md
2025-10-22T15:29:33.399Z [DPoPWebIdExtractor] {Primary} info: Verified WebID via DPoP-bound access token. [...]
2025-10-22T15:29:33.402Z [WebAclReader] {Primary} info: Found applicable ACL document [...]
2025-10-22T15:29:39.407Z [WrappedExpiringReadWriteLocker] {Primary} error: Lock expired after 6000ms on http://localhost:3000/alice/markdown.md

Expected behaviour

Either the new content should be saved successfully or the old content should still be present.