Open Radar

 
Area:
Finder

Summary:
Since macOS 10.13 High Sierra, a WebDAV drive sporadically unmounts without the user wanting to unmount. It happens especially if the WebDAV drive is "under high load".

Steps to Reproduce:
1. Connect to a WebDAV drive via Finder
2. Load many files into the WebDAV drive or save a file repeatedly

Expected Results:
WebDAV drive should stay connect and function normally

Actual Results:
WebDAV drive sometimes unmounts itself

Version/Build:
macOS 10.13.1 (but it already happened during the beta, even before the official 10.13.0 release)

Console:
Nov 15 15:21:34 <username> KernelEventAgent[104]: tid 54485244 received event(s) VQ_DEAD (32)
Nov 15 15:21:34 <username> KernelEventAgent[104]: tid 54485244 type 'webdav', mounted on '/Volumes/Usered00147', from 'https://webdavserver.com/Usered00147/', dead
Nov 15 15:21:34 <username> KernelEventAgent[104]: tid 54485244 force unmount https://webdavserver.com/Usered00147/ from /Volumes/Usered00147
Nov 15 15:21:34 <username> KernelEventAgent[104]: tid 54485244 found 1 filesystem(s) with problem(s)
Nov 15 15:21:34 <username> kcm[62480]: DEPRECATED USE in libdispatch client: Setting timer interval to 0 requests a 1ns timer, did you mean FOREVER (a one-shot timer)?
Nov 15 15:21:35 <username> NetAuthSysAgent[62478]: sendOptionsRequest: finalStatus(0)
Nov 15 15:21:35 <username> NetAuthSysAgent[62478]: WebDAV_OpenSession: not set to guest and user is NULL!
Nov 15 15:21:35 <username> NetAuthSysAgent[62478]: WebDAV_OpenSession: missing server credentials
Nov 15 15:21:35 <username> Microsoft Excel[62315]: open on /Volumes/Usered00147/Stat.xlsx: No such file or directory

Notes:
I've also attached a video to show the issue. The only thing I'm doing is opening an Excel file from a WebDAV drive and save it repeatedly. I've cut the video shorter. In reality, I had to save the file about a dozen times.

I also managed to reproduce the issue by creating many small files with "mkfile 1m {1..1000}.dat" and just copying them into the WebDAV drive.

I've tried several different WebDAV servers and the same issue exists on all of them. Even on WebDAV servers that are provided via localhost (loopback). Actually, this is how we've initially noticed the issue and it was definitely introduced with High Sierra because we never had such issues before that. https://github.com/cryptomator/cryptomator/issues/579