Files not transferred after server maintenance

Hi all! Need some help but I'm quite new to this so hopefully this makes sense.

I'm editing a website which originally was sharing an FTP accountwith another website. The server provider underwent maintenance to update their systems and the result is that I have had to create a new individual FTP account, which has gone through fine it seems.

But now whenever I push changes to the website in Dreamweaver this pops up (where before File activity went through fine and all operations were successful).

The updates to the website appear to still be going live which is good. But after reaching out to my server provider they can "confirm that everything on the server-side is configured properly, however, as the error message suggested the issue seems to be a local one. Prior to uploading files, please make sure that they are not opened by another application such as text editor, visual composers and etc".

I accept that maybe it is a local issue however I am unsure on how to rectify it and think it is unrealistic to close every single other application when uploading and using various different apps when editing a website, especially as it was not required before? And in any case that solution doesn't work.

If anyone has ever experienced this or can shed some light, that would be greatly appreciated!

Michelle

[image removed as per OP's request]