211 MB video file gets uploaded over and over again

Actual behaviour

Uploading a 211 MB movie file ("20-10-29 15-51-53 0188.mov"), it uploads the movie, having a short break at approx. 75 % and then continues up to the latest MB, then starts again from the beginning.

Probably this is because of the multiple retries you kindly added for me in #1395

Here are fragments from the communication.log that deal with the file in question:

...

2020-10-30 08:41:01 Start handle Events For Background URLSession: com.nextcloud.session.upload.background
2020-10-30 08:41:01 Network completed upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov with error code 404 and error description 404: The requested resource could not be found

...

2020-10-30 10:10:02 PROCESS-AUTO-UPLOAD find 1 items
2020-10-30 10:10:02 Network start upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov
2020-10-30 10:10:02 Automatic upload, no new assets found

...

2020-10-30 10:10:46 Start handle Events For Background URLSession: com.nextcloud.session.upload.background
2020-10-30 10:10:46 Network completed upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov with error code 404 and error description 404: The requested resource could not be found
2020-10-30 10:38:55 Check if location is enabled: authorizationStatus: 3

...

2020-10-30 10:38:55 PROCESS-AUTO-UPLOAD find 1 items
2020-10-30 10:38:55 Network start upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov
2020-10-30 10:38:55 Automatic upload, no new assets found
2020-10-30 10:38:55 The application did become active

...

2020-10-30 10:39:32 Network completed upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov with error code 404 and error description 404: The requested resource could not be found
2020-10-30 10:39:40 PROCESS-AUTO-UPLOAD find 1 items
2020-10-30 10:39:40 Network start upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov
2020-10-30 10:41:04 Network completed upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov with error code 404 and error description 404: The requested resource could not be found
2020-10-30 10:41:11 PROCESS-AUTO-UPLOAD find 1 items
2020-10-30 10:41:11 Network start upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov
2020-10-30 10:42:00 Network completed upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov with error code 404 and error description 404: The requested resource could not be found
2020-10-30 10:42:07 PROCESS-AUTO-UPLOAD find 1 items
2020-10-30 10:42:07 Network start upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov
2020-10-30 10:42:49 Network completed upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov with error code 404 and error description 404: The requested resource could not be found
2020-10-30 10:42:57 PROCESS-AUTO-UPLOAD find 1 items
2020-10-30 10:42:57 Network start upload file: https://cloud.uwe.co/remote.php/webdav/Photos/2020/10/20-10-29 15-51-53 0188.mov

...

iOS version

14.1

App version

Test Flight 3.0.10.19

Server configuration

Operating system:

Ubuntu (Linux 5.3.0-1032-aws x86_64)

Web server:

I'm using Snappy.

Database:

MySQL 5.7.31, I'm using Snappy.

PHP version:

7.3.21, I'm using Snappy.

Nextcloud version:

20.0.1, installed via Snappy

Start by tracing the background URLSession upload handling and the PROCESS-AUTO-UPLOAD flow described in communication.log. Investigate why the 404 completion leaves the 211 MB movie eligible for another upload; done means a failed upload is handled without repeatedly restarting the same file.