What do you guys do when you have time line of lets say 240 frames but you only cache out 50 frames of something. Now every time after 50th frame you get that error because for some reason Houdini can't simply play through whatever cache you got but has to be exact number like the timeline. So then my rendering doesn't work due to that error or causes bunch of other issues. How is it that cache has to be a length of full time line. What happens when I can't just cache 10000 frames of something?

you can for example append TimeShift SOP
set Clamp parm to Clamp Both
and reference your cache's Start/End Frame
this will make sure only that range will be evaluated so first and last cache frames will be held outside of that range

Another way (a poor man's solution really) could be to simply set the file node's "missingframe" parameter to "No Geometry" instead of "report error".

Depending on the situation, tamte's solution is cleaner though.

@tamte..oooh that's great thank you so much.

@protozan, that's cool solution too. I will try both in the context and see what works best. Thank you both so much for great tips.