Just trying lyx-2.1.0beta1 on fedora 19 linux. Loading up an old file, I got lots of errors related to image previews. These are all pdfs, and all produced by matplotlib. Strangely, the 1st file I loaded also had pdfs produced the same way and did not give errors.
Error: /rangecheck in --xyshow-- Operand stack: 0.0 4.65625 (\000p) --nostringval-- (\000p) --nostringval-- Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- -- nostringval-- 2 %stopped_push --nostringval-- --nostringval-- -- nostringval-- false 1 %stopped_push 1884 1 3 %oparray_pop 1883 1 3 %oparray_pop 1867 1 3 %oparray_pop 1755 1 3 %oparray_pop --nostringval-- %errorexec_pop .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- Dictionary stack: --dict:1168/1684(ro)(G)-- --dict:0/20(G)-- --dict:78/200(L)-- -- dict:67/75(L)-- --dict:19/25(L)-- --dict:10/15(L)-- --dict:2/15(L)-- Current allocation mode is local GPL Ghostscript 9.07: Unrecoverable error, exit code 1 lyx(20131)/kimgio: kimgio EPS: no image!