MTP device fails to mount

[Leo]

In 17.04 thunar/gvfs is no longer able to access my phone over USB. (This worked fine in 16.10 with the same phone/android version.)
On connecting the phone the device shows up in Thunar and double clicking it shows the two folders (Internal Shared Storage and SD Card), however another window immediately pops up saying:
Failed to mount "E5823"
Unable to open MTP device '[usb:003,048]'
The phone will then pop up the dialog asking how to use the USD connection (charging or transfer files) like when initially connected. Choosing Transfer causes the device to show up again in Thunar, but the same thing happens again if trying to access it.

The output of dmesg shows lots of lines like:
usbfs: process 13035 (events) did not claim interface 0 before use
and a few lines like:
usbfs: process 12893 (pool) did not claim interface 0 before use
where the process id changes every time I reconnect the device.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[JPT (j-p-t)]

usbfs: process <pid> (mtp.so) did not claim interface 0 before use

I get this error message on ubuntu 18.4.
I believe there are two different problems.

First problem could be that InternalSD is readonly to the MTP process on the phone (see last line in log), why?
Read-only requests worked.

The other problem are the failed read attempts with varying errno, see below.

Log from phone is:

05-28 15:32:02.505 D/MtpService(3263): Adding MTP storage 0x10001 at /storage/emulated/0
05-28 15:32:02.505 D/MtpService(3263): Adding MTP storage 0xa5bf0001 at /storage/7743-14FD
05-28 15:32:02.505 D/MtpService(3263): starting MTP server in MTP mode with storage /storage/emulated/0 disabled
05-28 15:32:13.094 E/MtpServer(3263): request read returned -1, errno: 5
05-28 15:32:13.551 D/MtpService(3263): starting MTP server in MTP mode with storage /storage/emulated/0
05-28 15:32:13.558 D/MtpService(3263): Adding MTP storage 0xa5bf0001 at /storage/7743-14FD
05-28 15:32:13.558 D/MtpService(3263): Adding MTP storage 0x10001 at /storage/emulated/0
05-28 15:32:26.711 E/MtpServer(3263): request read returned -1, errno: 5
[ above repeated several times. ]

05-28 15:35:30.269 D/MtpService(3263): Adding MTP storage 0xa5bf0001 at /storage/7743-14FD
05-28 15:35:30.270 D/MtpService(3263): Adding MTP storage 0x10001 at /storage/emulated/0
05-28 15:35:53.914 E/MtpServer(3263): deletePath stat failed for /storage/emulated/0/DCIM/Camera/IMG_20180519_202734.jpg: No such file or directory
[repeated for each file]