I had the same error…
Problem fetching data from dump1090.
AJAX call failed (error: Not Found). Maybe dump1090 is no longer running?
The displayed map data will be out of date.
I fixed it by following these steps:
#open file rtl-sdr-blacklist.conf for editing
sudo nano /etc/modprobe.d/rtl-sdr-blacklist.conf#add the following 2 lines to above file:
blacklist dvb_usb_rtl2832u
blacklist dvb_usb#save file
#get the vendor and product ID from your USB receiver
lsusb#note that line which is related to your stick (e.g. Bus 003 Device 018: ID 0bda:2832 Realtek Semiconductor Corp. RTL2832U DVB-T)
#open file rtl-sdr.rules for editing
sudo nano /etc/udev/rules.d/rtl-sdr.rules#add the following line to above file and change the id’s, matching your device:
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2832", MODE:="0666"#save file
#exit and reboot
sudo reboot
Raspbian Stretch + dump1090-mutability~1.15dev is running fine now. 