Creating 0-byte size files on the Webdav-Server, any reading results in I/O error. First I thought the issue is a bug on the Webdav Server. But with a different client, using Windows Explorer, I can't reproduce.

Steps to reproduce:
1. Create a 0-byte file "0-byte-Windows" from Windows Explorer or any other Webdav client.

2. Mount from Linux:

$ mount.davfs -V
davfs2 1.5.4

$ mount |grep dav
https://sd2dav.1und1.de/ on /mnt/sd2dav type fuse (rw,nosuid,nodev,noexec,relatime,user_id=4728,group_id=4728,allow_other,max_read=16384,uid=4728,gid=4728,user=mb,helper=davfs)

$ cd /mnt/sd2dav

$ stat 0-byte-Windows
  File: 0-byte-Windows
  Size: 0         Blocks: 0          IO Block: 4096   regular empty file
Device: 3eh/62d Inode: 93931767225792  Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 4728/      mb)   Gid: ( 4728/      mb)
Access: 2018-11-30 11:17:37.000000000 +0100
Modify: 2018-11-30 11:17:22.000000000 +0100
Change: 2018-11-30 11:17:22.000000000 +0100
 Birth: -
$ md5sum 0-byte-Windows
md5sum: 0-byte-Windows: Input/output error

However creating a 0-byte file from the local mount works:

$ touch 0-byte-Linux
$ md5sum 0-byte-Linux
d41d8cd98f00b204e9800998ecf8427e  0-byte-Linux

But every 0-byte file created from any other clients fails to be synced or read. I guess this is some bug on the caching or something.

Weird enough, on Android the app "FolderSync" has the same issue, which cannot be reproduced with Windows Explorer either. Maybe some library on Android is similar to davfs2.

I don't have any other reference client or testing webdav server.