Issue #19354 has been updated by nobu (Nobuyoshi Nakada). Status changed from Open to Feedback `IO.read` opens the file given as the first argument, then delegates the other arguments to `IO#read` on the instance. Your error happens in the delegated `IO#read`. Since 3.0, keyword arguments are separated from mere hashes. I think you may want to write: ```ruby IO.read("a.txt", 3, 0, mode: "r+") ``` ---------------------------------------- Bug #19354: Issues with arguments validation in IO.read https://bugs.ruby-lang.org/issues/19354#change-101348 * Author: andrykonchin (Andrew Konchin) * Status: Feedback * Priority: Normal * ruby -v: 3.2.0, 3.1.3 * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- I've noticed a strange error message when `IO.read` is called with additional positional argument: ```ruby IO.read("a.txt", 3, 0, {mode: "r+"}) # (irb):2:in `read': wrong number of arguments (given 3, expected 0..2) (ArgumentError) ``` But I would expect receiving `given 4, expected 1..3` as far as the first argument (file name) is mandatory and all the other arguments - are optional. I've encountered another related issue - looks like existing of a file with specified name is checked **before** number of arguments. So when passed additional argument and specified a name of not existing file - I receive error about wrong file name, but would expect more basic and essential error about wrong number of arguments: ```ruby IO.read("b.txt", 3, 0, {mode: "r+"}) # (irb):3:in `read': No such file or directory @ rb_sysopen - b.txt (Errno::ENOENT) ``` -- https://bugs.ruby-lang.org/