Mismatch: X:1 doesn't match requested X:3
X:3 not found in http://thesession.org/tunes/1569

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.60 512x512 ]
filesizedescription
Tune-20790-1569.abc 0 ABC music file with the extracted tune(s)
Tune-20790-1569.txt 0 Plain-text file with the extracted tune(s)
Tune-20790-get.log 3354 Log file, useful mostly for debugging
These files should be available for 24 hours.