Issue with filenames with spaces

I’ve uploaded some files with the UI Builder Upload Button. The name of those files contain spaces and “+”-characters. The result is, that I cannot delete those files anymore from the console file browser (“File or directory cannot be found”).

I think the reason is, that the file upload button is returning a “half way” url encoded file url. Spaces get replaced by “+”-characters and the “+”-character is encoded as %2B. However, this is not how the files are then represented on the backendless file system.

I’ll send you the details about my non-deletable files via email. Please remove them for me.

To avoid such situations, I’m using a file name logic for the file upload button which looks like this:

However, it would be good if there wouldn’t be the need to do this!


Hello @Klaas_Klever

Please provide your app id, and non-delectable files here if you can.

Regards, Dima.

I‘ve sent it per Email to

I have created an internal ticket(BKNDLSS-25144) to investigate your issue and deleted these files.

Thank you for informing us.

Regards, Dima.

Hello @Klaas_Klever

We’ve just updated cloud servers with a fix for the issue you described above. Could you kindly let us know whether fix works for you well?


No. I can still provoke an error by using “funny” characters in filenames, although these “funny” characters are valid filename characters for my Windows system.

Here is an example of such a filename: 1630416429171,p-104__v-7x2@2dL_-bc8ecb.jpg

This causes the error: Error: Path contains prohibited symbols:

For cleaning up such filenames I’m using the “File Name Logic” handler with the following substitution:

This works at least for all funny filenames I’ve met so far …


Hello @Klaas_Klever,

I’ve reopented the internal ticket BKNDLSS-25144. Our developer will check it as soon as possible.


Here is an update of my Regex. I’ve found that the “=”-character is also a “bad” one :slightly_smiling_face:


Thanks @Klaas_Klever, I’ve added this info to the ticket. We’re still working on it and will let you know once it is fixed.

Thank you for your patience!