On numerous times (not always), I get an error on my download when it is about to finish "HTTP error 404" which stops the file from being completly downloaded..

How to avoid this issue from recurring?

I'm using the FireFox browser (latest v 50.1.0), and I have the latest FDM v5.1 installed, I'm facing a problem that FDM sometimes do not catch all sites downloads (e.g it works/catches downloads from keep2share, but NOT from rapidgator), is there a way to fix this problem (I already installed the ...

I'm using the FireFox browser (latest v 50.1.0), and I have the latest FDM v5.1 installed, I'm facing a problem that FDM sometimes do not catch all sites downloads (e.g it works/catches downloads from keep2share, but NOT from rapidgator), is there a way to fix this problem (I already installed the F...