I've been running MATE 18.04 for about a month and two weeks ago I started to getting the popup message "Unable to mount location - Failed to retrieve share list from server: No such file or directory".
I have read all the treads with this topic and searched to web and non of the solutions offered have worked. Looking for help to resolve.
Have you tried connecting directly to the IP# using smb? smb://ip#
What type of server are you connecting to? What OS is that system running?
@jaybo's suggestion of mounting via the command line is a good idea to try.
Basically, you don't have a WINS server (or whatever it's called these days) - basically, the Windows version of DNS. The only way I can see an environment STOP working the way you describe though is if you changed your router or something like that: otherwise, it would simply never have worked in the first place. (That, or a FW update to the device you're trying to use - a NAS or etc - disabled it).
hmm... that does bring up one possibility: SMB1 is now officially dead. If your server / device / whatever was using that to respond to requests (or vv from the client side) and one of those sides has shut it off in the last couple of weeks, that would do it.
Start with jaybo's suggestion, then try manually mounting the device (caja etc are no good for this sort of thing) with "vers=x.0" if that doesn't work. If you're still not having any luck then unfortunately you'll probably have to delve into various settings / config files / etc to sort things out, but hopefully it won't come to that.
I did what Jaybo recommended and it worked. However, I'm trying to understand why select in Windows Network two weeks ago and it showed the shares on my on my MAC's, Windows PC's to not working today. With that said I think it may be related to my attempt to share folders on Ubuntu Mate desktop. I have an ASUS laptop running 18.04 and selecting Windows Networks in Caja works.
I can't explain it, but I have observed the same where sometimes I can connect via the shared names and other times not. I finally just resorted to the IP#.
Weird. That sounds like you do have a WINS server (but you don't know about it, which means it's probably part of your router's functionality) but it's unreliable for some reason (different lifetimes on the names maybe?), or one of your PCs is providing the resolution, or too many things to guess at really.
Depending on how your LAN is set up, you might want to use /etc/hosts for some of the devices on it. (You can only do this if they have static IPs). It'll save you a lot of awkward typing. Just add lines like this:
192.168.1.7 nas
to the file, after which you can just use "smb://nas" to connect to it rather than "smb://123.456.7.890".
(I do this for my setup, so the servers have assigned IPs but everything else uses DHCP so I don't have to micromanage the whole LAN).