How do I disconnect the MTP connection between Dolphin (file manager) and my tablet so that Calibre can connect to the tablet?

According to https://manual.calibre-ebook.com/faq.html#android-usb
Note that on macOS and Linux only a single program can connect to an Android device at a time, so make sure the device is not opened in the OS File manager, or the Android File Transfer utility, etc.

Calibre does not connect to my Samsung Tab A 10.1" (2016).
How do I disconnect the MTP connection between Dolphin (file manager) and my tablet so that Calibre can connect to it?

As soon as I press "allow" access on the tablet, I get a notification asking me if I want to browse the files on the tablet, view pictures, etc. I'm assuming this is when the device is "opened in the OS File manager".

I am able to transfer files to/from my tablet through Dolphin if I need to.
I made sure to remove any other MTP programs that might interfere (android-file-transfer, mtpfs, jmtpfs, simple-mtpfs, go-mtpfs-git). libmtp is installed as a requirement by kio-extras.
I have kio-extras installed as my way to connect to the tablet through Dolphin.

This is the "Debug device detection" log generated by Calibre:

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u''],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u''],
 ['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455'],
 ['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=13, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=13, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=13, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=13, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'proton0': [{'addr': u'10.50.0.23', 'netmask': u'255.255.0.0', 'peer': u'10.50.255.255'}], u'lo': [{'addr': u'127.0.0.1', 'netmask': u'255.0.0.0', 'peer': u'127.0.0.1'}], u'enp37s0': [{'addr': u'192.168.0.201', 'netmask': u'255.255.255.0', 'broadcast': u'192.168.0.255'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=13, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7f0c15e18750>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

If your tablet is an Android tablet, which it looks like it is -- if you drag down your statusbar -- you'll have an option to modify which state your USB connection is in. Click on it and a menu should appear. In that menu, if you are on "File connection", that means ADB/MTP is active. You can switch that to "Charging only" or the relative option for that.

That should disable MTP and allow you to use this Calibre application.

I have switched it to charging only but it still doesn't get detected by Calibre.

Here's what I else I've tried:

Allow connection to computer. USB file transfer in drop down menu. USB Debugging mode off. Dolphin not open. Not detected.

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455'],
 ['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u''],
 ['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=34, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=34, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=34, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=34, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'proton0': [{'addr': u'10.50.0.10', 'netmask': u'255.255.0.0', 'peer': u'10.50.255.255'}], u'lo': [{'addr': u'127.0.0.1', 'netmask': u'255.0.0.0', 'peer': u'127.0.0.1'}], u'enp37s0': [{'addr': u'192.168.0.201', 'netmask': u'255.255.255.0', 'broadcast': u'192.168.0.255'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=34, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7f1eb9822850>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

Deny connection to computer. USB file transfer in drop down menu. USB Debugging mode off. Dolphin not open. Not detected.

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455'],
 ['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u''],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=27, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=27, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=27, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=27, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'proton0': [{'netmask': u'255.255.0.0', 'peer': u'10.50.255.255', 'addr': u'10.50.0.10'}], u'lo': [{'netmask': u'255.0.0.0', 'peer': u'127.0.0.1', 'addr': u'127.0.0.1'}], u'enp37s0': [{'netmask': u'255.255.255.0', 'broadcast': u'192.168.0.255', 'addr': u'192.168.0.201'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=27, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7ffb72bb6750>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

Deny connection to computer. USB charge only in drop down menu. USB Debugging mode off. Dolphin not open. Not detected.

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u''],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u''],
 ['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=32, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=32, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=32, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=32, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'lo': [{'netmask': u'255.0.0.0', 'addr': u'127.0.0.1', 'peer': u'127.0.0.1'}], u'enp37s0': [{'netmask': u'255.255.255.0', 'broadcast': u'192.168.0.255', 'addr': u'192.168.0.201'}], u'proton0': [{'netmask': u'255.255.0.0', 'addr': u'10.50.0.10', 'peer': u'10.50.255.255'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=32, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7ff4508bf890>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

**Allow connection to computer. Change tablet setting to charge only in developer settings after plugging in. USB Debugging mode off. Dolphin not open. Not detected. **

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u''],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
No MTP devices connected to system
 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'lo': [{'peer': u'127.0.0.1', 'netmask': u'255.0.0.0', 'addr': u'127.0.0.1'}], u'enp37s0': [{'broadcast': u'192.168.0.255', 'netmask': u'255.255.255.0', 'addr': u'192.168.0.201'}], u'proton0': [{'peer': u'10.50.255.255', 'netmask': u'255.255.0.0', 'addr': u'10.50.0.10'}]}
No device is connected
 
Looking for devices...
 
Devices possibly connected: None

Allow connection to computer. USB file transfer in drop down menu. USB Debugging mode on. Dolphin not open. Not detected.

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u''],
 ['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455'],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=44, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=44, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=44, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=44, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'enp37s0': [{'netmask': u'255.255.255.0', 'broadcast': u'192.168.0.255', 'addr': u'192.168.0.201'}], u'lo': [{'netmask': u'255.0.0.0', 'addr': u'127.0.0.1', 'peer': u'127.0.0.1'}], u'proton0': [{'netmask': u'255.255.0.0', 'addr': u'10.50.0.10', 'peer': u'10.50.255.255'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=44, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7ffae8253890>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

Allow connection to computer. USB charge only in drop down menu. USB Debugging mode on. Dolphin not open. Not detected.

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u''],
 ['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455'],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=47, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=47, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=47, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=47, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'lo': [{'addr': u'127.0.0.1', 'netmask': u'255.0.0.0', 'peer': u'127.0.0.1'}], u'enp37s0': [{'addr': u'192.168.0.201', 'broadcast': u'192.168.0.255', 'netmask': u'255.255.255.0'}], u'proton0': [{'addr': u'10.50.0.10', 'netmask': u'255.255.0.0', 'peer': u'10.50.255.255'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=47, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7fedfa06b750>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

Allow connection to computer. USB charge only in drop down menu. USB Debugging mode off. Dolphin not open. Not detected.

calibre 4.19  embedded-python: True is64bit: True
Linux-4.19.126-1-MANJARO-x86_64-with-glibc2.2.5 Linux ('64bit', 'ELF')
('Linux', '4.19.126-1-MANJARO', '#1 SMP Wed Jun 3 22:30:22 UTC 2020')
Python 2.7.16
Linux: ('', '', '')
Interface language: None
USB devices on system:
[['0x1235', '0x8205', '0x41c', u'Focusrite', u'Scarlett Solo USB', u''],
 ['0x4e8',
  '0x6860',
  '0x400',
  u'SAMSUNG',
  u'SAMSUNG_Android',
  u'52034f32b219b455'],
 ['0x3842', '0x2410', '0x2801', u'EVGA', u'EVGA TORQ X10 Gaming Mouse', u''],
 ['0xc45', '0x6510', '0x100', u'SONiX', u'USB DEVICE', u'']]

No disabled plugins
Looking for devices of type: MTP_DEVICE
MTP devices connected:
USBDevice(busnum=1, devnum=30, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)

Trying to open: USBDevice(busnum=1, devnum=30, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
Opening device failed:
Traceback (most recent call last):
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 150, in debug_managed_device_detection
  File "site-packages/calibre/devices/mtp/driver.py", line 125, in open
  File "site-packages/calibre/devices/mtp/base.py", line 25, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 224, in open
OpenFailed: Failed to open USBDevice(busnum=1, devnum=30, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455): Error: Unable to open MTP device with busnum=1 and devnum=30, tried 1 such devices

 
Looking for devices of type: SMART_DEVICE_APP
All IP addresses {u'lo': [{'netmask': u'255.0.0.0', 'peer': u'127.0.0.1', 'addr': u'127.0.0.1'}], u'enp37s0': [{'netmask': u'255.255.255.0', 'broadcast': u'192.168.0.255', 'addr': u'192.168.0.201'}], u'proton0': [{'netmask': u'255.255.0.0', 'peer': u'10.50.255.255', 'addr': u'10.50.0.10'}]}
No device is connected
 
Looking for devices...
USBDevice(busnum=1, devnum=30, vendor_id=0x04e8, product_id=0x6860, bcd=0x0400, manufacturer=SAMSUNG, product=SAMSUNG_Android, serial=52034f32b219b455)
		Detected possible device ANDROID
 
Devices possibly connected: Android driver,  
Trying to open Android driver ... failed
Opening of the following devices failed
<calibre.devices.android.driver.ANDROID object at 0x7f6a5a005810>
Traceback (most recent call last):
  File "site-packages/calibre/devices/__init__.py", line 159, in debug
  File "site-packages/calibre/devices/usbms/device.py", line 812, in open
  File "site-packages/calibre/devices/usbms/device.py", line 565, in open_linux
DeviceError: Unable to detect the ANDROID disk drive. Either the device has already been ejected, or your kernel is exporting a deprecated version of SYSFS.

Calibre's developer said:

On linux, only one program can access an MTP device at a time. Prevent
your desktop environment from mounting the device and it will work in
calibre.

How do I prevent the desktop environment from mounting the device?

Try installing these packages from AUR and maybe they will assist in your efforts:

sudo pacman -S mtpfs android-tools android-udev

Make sure you don't do anything when plasma notify you about your tablet being connected..(do not choose to browse). And check in system setting there is a place about auto mounting device.. I don't remember exactly where right now and I'm not on my computer.

I installed them and rebooted the computer. I left the tablet connected to the computer.
After I unlocked and allowed access to the tablet, Calibre was able to communicate with the tablet.
I uninstalled mtpfs, android-tools, android-udev and rebooted the computer.
After I unlocked and allowed access to the tablet, Calibre was able to communicate with the tablet.

I unplugged and plugged back in the tablet while the computer was in the desktop environment. Calibre is unable to communicate with the tablet, but I can browse the tablet's files in Dolphin.

Logging off and back in does not give Calibre access to the tablet, but I can browse the tablet's files in Dolphin.

For now I'll remind myself to plug in the tablet and reboot the computer anytime I need to use a program with an MTP device.

"Removable Devices"
I've had the main option "Enable automatic mounting of removable media" unchecked throughout my troubleshooting.

Yes, I made sure not to click on any pop-ups related to the tablet or clicking on the tablet entry in Dolphin.

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