"Unable to write", what to do?

My Windows client stopped synchronizing today with the red error:
“Unable to write path/to/large/iso/file.iso: Unable to write”

There is no resume button or anything.

Although there are more files in the queue, it does not continue transferring (uploading) on that account.

In the log console F12 I don’t see anything related, only new messages are coming in. There are messages like these:

08-01 18:03:34:521 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:34:521 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:34:523 0x3b7c88 OCC::FolderMan::slotRunOneEtagJob: Scheduling "ht tps://cloud.mydomain.com/remote.php/webdav/" to check remote ETag
08-01 18:03:34:523 0x3b7c88 OCC::AbstractNetworkJob::start: !!! OCC::RequestEtagJob created for "ht tps://cloud.mydomain.com" + "/" "OCC::Folder"
08-01 18:03:34:823 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:34:824 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:34:825 0x3b7c88 OCC::FolderMan::slotRunOneEtagJob: Scheduling "ht tps://cloud.mydomain.com/owncloud/remote.php/webdav/" to check remote ETag
08-01 18:03:34:826 0x3b7c88 OCC::AbstractNetworkJob::start: !!! OCC::RequestEtagJob created for "ht tps://cloud.mydomain.com/owncloud" + "/" "OCC::Folder"
08-01 18:03:35:111 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:35:112 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:35:113 0x3b7c88 OCC::FolderMan::slotRunOneEtagJob: Scheduling "ht tps://cloud.mydomain.com/owncloud/remote.php/webdav/" to check remote ETag
08-01 18:03:35:113 0x3b7c88 OCC::AbstractNetworkJob::start: !!! OCC::RequestEtagJob created for "ht tps://cloud.mydomain.com/owncloud" + "/" "OCC::Folder"
08-01 18:03:35:423 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2
08-01 18:03:35:423 0x3b7c88 unknown: QString::arg: Argument missing: "ht tps://docs.nextcloud.com/desktop/2.2/" , 2

The file size is 3 325 056 KB (3gb). smaller and larger files have uploaded already today or yesterday, the largest being 3 958 649 KB (4gb). Therefore it can’t be a file size problem.

nextcloud runs on a vm and has enough free disk space (26% used):

user@nextcloud:~$ df
Filesystem                      1K-blocks      Used Available Use% Mounted on
udev                               488068         0    488068   0% /dev
tmpfs                              101620     11152     90468  11% /run
/dev/mapper/nextcloud--vg-root 1055233292 259483952 742123484  26% /
tmpfs                              508096         0    508096   0% /dev/shm
tmpfs                                5120         0      5120   0% /run/lock
tmpfs                              508096         0    508096   0% /sys/fs/cgroup
/dev/loop1                           4736      4736         0 100% /snap/spreedme/22
/dev/sda1                          482922     58546    399442  13% /boot
tmpfs                              101620         0    101620   0% /run/user/1000
/dev/loop4                          81408     81408         0 100% /snap/core/2312
/dev/loop6                          82432     82432         0 100% /snap/core/2381
/dev/loop5                          82432     82432         0 100% /snap/core/2462

the host operating system also has 515 GB free.

My Windows client is version 2.2.4 (build 2) running on Windows 8.1.

My server is version 11.0.1 (stable) running on some kind of Linux. In the web gui admin in “Additional settings” it tells me that the maximum upload size is 511 MB. But as written above I’ve got a 4GB file uploaded, and I’m sure nextcloud is smart enough to use some kind of file splitting.

In the web admin console under Logging I see a lot of these:

Error	PHP	Module 'smbclient' already loaded at Unknown#0
and then a few of these:
Fatal	webdav	Sabre\DAV\Exception\BadRequest: ht tp/1.1 400 expected filesize 10000000 got 1443392
Fatal	webdav	Sabre\DAV\Exception\BadRequest: ht tp/1.1 400 expected filesize 10000000 got 5066560
Fatal	webdav	Sabre\DAV\Exception\BadRequest: ht tp/1.1 400 expected filesize 10000000 got 9000000

Files were still uploaded after the first such webdav errors I see by timestamp.

Why doesn’t it auto-resume?
How can I tell it to resume?
Where can I get more information about what the problem is?

As a power user I might be able to find a way around this, but my friends will need a solution that is fault tolerant and self healing and doesn’t just stop working without any hint of what to do.

PHP 7.0.15
Memory limit 512 MB
Max execution time 3600
Upload max size: 511.0 MB

DB MySQL 5.7.19, 80.8MB

Storage: 5 users, 132 130 files

In the Windows client, activity tab, Sync Protocol I see that the last file was uploaded 3 hours ago. “Server Activity” tab confirms this. After that there is no more log entry.

Help system notice: New users may only put 2 links in a post. These are not links, they are URLs appearing in the requested log file content.

The Windows client removed the error message and says it is syncing. The file is not up yet, but it seems to be working on that.

In that case it looks like it’s working fine, it’s just unfortunate how it’s displayed, without info that it will resume, without possibility to “resume now” or “skip file”.

For this error, there a a bunch of parameters that influence this setting, a nice summary from owncloud which should still be valid for Nextcloud:

The file got uploaded and it continues with other files. I did not have to do anything to make it recover and resume.

So this is a display problem only. Really not clear what to expect and what to do as end user. My suggestion is a text info that it will retry later, and a button to retry now.

For user experience, better error messages, please report here: github.com/owncloud/client/issues