I am using Apm 2.6 with U-blox Neo 6M for my quadcopter. After every flight whenever I review my ‘Data Flash Log’ , it shows an error GPS FAILED, also “Err. FAILSFAE_GPS-0” , “Err.FAILSAFE_GPS-0”.
Also the Gps HDOP value never goes below 2.

At times I get BROWNOUT problems. I have attached two logs of the latest flight for reference purpose. Is it the problem with the GPS or some other reason.
2016-05-21 08-19-19.bin (35.6 KB)
2016-05-21 08-12-25.bin (83.0 KB)

Can someone help me with this problem and also if there is any other issues that I be should taking care of, please suggest some solution for it. Its been more than a month and I am not able to find good possible solution for it.