Suppose a CVS -n update throws the following error:
cvs update: inflate: unknown compression methodcvs [update aborted]: reading from server: Input/output error
When you use the -n option, there’s a mismatch in the zlib version used by the CVS server and client?which is causing the error. The only way to fix this is to bring them both in sync. Updating your CVS client (or downgrading it) should fix the problem.