I'm trying to get access to my Samsung phone's contents under Linux (Mint 20.3), but not having much luck.
My primary goal is to copy music files from my computer to the phone, but I can't seem to get the damned thing (the phone) to mount reliably so that I can do that.

I've tried the adb tools, and although the "adb devices" command does recognize the phone, the system a whole does not. I've also tried to access the phone's music library directly through Clementine (my computer's music player), but every time I click on my phone's listing under Clementine's "Devices" list, Clementine just crashes out.

In the end, I'd ideally like to find a user-friendly way of accessing, browsing, and backing up my phone's overall contents. Any suggestions?

Please forgive my ignorance with this question, but are you trying to connect via bluetooth or USB cable?
Open a terminal, and run:
Note: the "-w" will follow:
Now try to connect the phone, you may get some idea on what's happening with dmesg...

On my A52 i have to have the phone unlocked FIRST

Then tap the " allow" option that pops up on the phone when i plug in the usb cable

Well I'll be damned John VV- I think you just might have hit on the answer to my immediate question/problem.
I unlocked my phone (a Galaxy A32) before connecting the USB cable as you suggested, hit "Allow" at the prompt on the phone once I did connect the cable, and voila- the entire contents of the phone were mounted and accessible.
I've just begun to try to copy my computer's current Music library to the phone, which will take a bit of time... I'll let you know how it goes.

Update: On my first attempts to copy my *entire* music collection from my computer to my phone, the process repeatedly choked with file-copy errors somewhere around half-way through the copy process. But on retrying the process by selecting only about 1/4 of library contents at a time, I was able to successfully complete the entire transfer.

Not only that, but since your solution to mounting my phone also gave me access to all of the folders on the phone, I was able to browse through those folders and weed out a lot of cruft that would have taken me much longer to delete if I had to do that on the phone itself.

Thanks again for you suggestion!

dc.901- thank you for responding, and My Bad for not indicating that I was connecting via USB (the computer I'm using doesn't have BlueTooth).

Since John VV posted an answer that solved my immediate issue though, I think I'll leave my larger questions of getting Android phones to generally "play nicely" with Linux for another time.

Hi. It may be memory problem. With oldest PCs (PIII 1000Mhz 512Mb), copy little files from PC to pendrive has the same problem: can not copy all those files. But copying in batchs, it can do.

In the fstab file i put 'async' option for pendrives or SDs. With 'sync' option the copy of files take a lot of time.

Have a nice day.

Hi cesarbergara, and thank you for your reply.
However, it turns out that my file-copy errors resulted from errors in my source library. Once I sorted those out, my file-copy went through just fine.

Thank you for sharing.