# Known Issues and Limitations

- The only way to determine whether uploads have failed is to look at the ‘Operational Statistics’ page linked from the Welcome page. This only shows a count of failures, not the names of files. Uploads are never retried.
- The Magic Folder frontend performs its uploads sequentially (i.e. it waits until each upload is finished before starting the next), even when there would be enough memory and bandwidth to efficiently perform them in parallel. A Magic Folder upload can occur in parallel with an upload by a different frontend, though. (#1459)
- On Linux, if there are a large number of near-simultaneous file creation or change events (greater than the number specified in the file `/proc/sys/fs/inotify/max_queued_events`), it is possible that some events could be missed. This is fairly unlikely under normal circumstances, because the default value of `max_queued_events` in most Linux distributions is 16384, and events are removed from this queue immediately without waiting for the corresponding upload to complete. (#1430)
- The Windows implementation might also occasionally miss file creation or change events, due to limitations of the underlying Windows API (ReadDirectoryChangesW). We do not know how likely or unlikely this is. (#1431)
- Some filesystems may not support the necessary change notifications. It is recommended for the local directory to be on a directly attached disk-based filesystem, not a network filesystem or one provided by a virtual machine.
- If a file in the upload directory is changed (actually relinked to a new file), then the old file is still present on the grid, and any other caps to it will remain valid. Eventually it will be possible to use garbage collection to reclaim the space used by these files; however currently they are retained indefinitely. (#2440)
- Unicode filenames are supported on both Linux and Windows, but on Linux the local name of a file must be encoded correctly in order for it to be uploaded. The expected encoding is that printed by `python -c "import sys; print sys.getfilesystemencoding()"`.
- On Windows, local directories with non-ASCII names are not currently working. (#2219)
- On Windows, `magic-folder run` may be unresponsive to Ctrl-C (it can only be killed using Task Manager or similar). (#2218)