Support intro
Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 20.0.5): 20.0.7
Operating system and version (eg, Ubuntu 20.04): Mint 19
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.25
PHP version (eg, 7.4): 7.4
The issue you are facing:
Two of my files cannot be uploaded into my server.
Is this the first time you’ve seen this error? (Y/N): Y
Steps to replicate it:
- Place
Александра Прокошина Пётр Казьмин Женская группа Государственного академического русского народного хора имени - И кто его знает？.mp3
and
Оркестр Государственного академического Большого театра СССР Геннадий Рождественский Хор Государственного академ - Интернационал.mp3
into the sync folder. - Wait for the automatic upload.
- The former return “Connection closed”, and the latter “500 Internal Server Error”. Both can’t be uploaded, but won’t block the syncing process.