Writer nodes don't work with mounted network drives on Windows

Continuing the discussion from No write permissions on mapped network drive (Windows 7):

Just wanted to revive this old topic saying that in current versions of KNIME, this unfortunately isn’t “only a message” in the dialog: the Writer nodes refuse to work when trying to write on mounted network volumes on Windows.

You may need to access drive/folder to be able to read or write. I have to open say Y: drive before I can read it in other case reader fails.

I was specifically talking about the Writer nodes. The Reader nodes work for me, but the writers complain, no matter if I accessed the folder in Windows Explorer before or not.

Dear @knime :knime: team,

is there any update on this? The Writer nodes still suffer from this limitation in the latest version of KNIME Analytics Platform.

Hi @imagejan,

Can you please post the format of your output URL, as well as the error message you are seeing?


Hi @RolandBurger,

Sorry for the delay in following up.

I prepared a small sample workflow that shows where the writer nodes fail to write on our network file system, even if I have write permissions.

Writer node issues.knwf (39.5 KB)

The error messages are:

  • Image Writer:

    • path W:\...

      ERROR Image Writer         2:2        Execute failed: Output directory 'W:\scratch\gmicro\eglijan\test' is not writable
    • path \\tungsten-nas.fmi.ch\...

      ERROR Image Writer         2:6        Execute failed: Output directory '\\tungsten-nas.fmi.ch\scratch\gmicro\eglijan\test' is not writable
  • CSV Writer:

    • path W:\...

      WARN  CSV Writer           2:4        Directory 'W:\scratch\gmicro\eglijan\test' is not writable

      … even though this is merely a warning, I can’t execute the node.

    • path \\tungsten-nas.fmi.ch\...

      • works fine :white_check_mark:
  • XML Writer (node not executable):

    • path W:\...

      WARN  XML Writer           2:5        Output directory 'W:\scratch\gmicro\eglijan\test' is not writable
    • path \\tungsten-nas.fmi.ch\...

      WARN  XML Writer           2:10       Output directory '\\tungsten-nas.fmi.ch\scratch\gmicro\eglijan\test' is not writable

All above cases point to the same directory, and I have write permission, as shown by the successful writing with the CSV Writer in the second case.

My suspicion is that the issue exists because the implementation at some point checks Files.isWritable or something similar, which is not always guaranteed to give accurate results. The only way to check if you have write permission is to actually try writing to a file. In this direction, it would be very helpful if the nodes above could be made executable even if they’re issuing these warnings.

Thanks for your support.