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Ignored - and otherwise problematic - files and filenames

In general, the Nextcloud synchronization client is able to upload and synchronize files and folders between the online version and your local copy. There are, nevertheless, some restrictions that can affect a successful upload of your data, depending on several factors:

  • Your operating system
  • The type of data you upload
  • The Nextcloud client
  • How you connect to Sunet Drive

A detailed description on files that are being ignored can be found here and can be summarized as:

  • Files starting with: .sync*.db*, .sync_*.db*, .csync_journal.db*, .owncloudsync.log*; these are files used bye the client itself
  • Filenames with more than 254 characters
  • The file Desktop.ini
  • Files matching *_conflict-* since they are reserved for conflict file resolution
  • On Windows only: Files that do not work on Windows filesystems: (\, /, :, ?, *, ", >, <, |)
  • On Windows only: Files with a trailing space or dot
  • On Windows only: Filenames that are reserved on Windows

Out of own experience, it is also not recommended to use filenames containing the percentage-sign (%), since these can represent different characters in URLs (also known as percent-encoding). In general, you should also be careful using filenames with Unicode-characters and spaces (“Åsnan äter hö.docx”). They might work without a problem on your computer(s), but not on one of your collaborators.

Btw.: Many IT systems do not allow certain characters. This article for example could not be called “Ignored (and otherwise problematic) files and filenames” because of the brackets.

A note about file name length: The limit of how long a path to a file can be in Sunet Drive, is limited by among other things operating system/file system limits. In a default Windows 10 installation that limit is roughly 256 characters. Other operating systems and file systems usually have longer, but not unlimited restrictions on the length of the filename including the path. That means that it could be possible to create a file with a long name on one system, that can not be synched to another. To be safe, and be sure that users do not experience issues related to the length of the filename, it is recommended to stay below 256 characters, even if longer filenames might work for some users.

The true absolute upper limit, that will not work for anyone is 1 024 bytes (some characters take up more than one byte, but if you follow the guidelines above, about which Unicode characters you use, a byte can be considered the same as a character).