Issue #20607 has been updated by jeremyevans0 (Jeremy Evans). I submitted a pull request to make the error message consistent: https://github.com/ruby/ruby/pull/11097 ---------------------------------------- Bug #20607: Exception messages are inconsistent when thread-local variables are accessed https://bugs.ruby-lang.org/issues/20607#change-108948 * Author: andrykonchin (Andrew Konchin) * Status: Open * ruby -v: 3.2.4 * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- `Thread`'s methods to manipulate thread-local variables raise `TypeError` exceptions with slightly different messages when the `key` argument is not a String or a Symbol. The message is either `is not a symbol` or `is not a symbol nor a string`. As far as both String and Symbol arguments are correct it seems the `is not a symbol nor a string` message is more accurate and should be used consistently. The following methods raise `is not a symbol` error: ```ruby @t.thread_variable_set(:a, 0) # for some methods it's important to have some thread-local variables assigned @t.thread_variable_get(123) # => 123 is not a symbol (TypeError) t.thread_variable_set(123, 1) # => 123 is not a symbol (TypeError) t.thread_variable?(123) # => 123 is not a symbol (TypeError) t[123] = 1 # => 123 is not a symbol (TypeError) ``` The following methods raise `is not a symbol nor a string` error: ```ruby t.fetch(123) # => 123 is not a symbol nor a string (TypeError) t.key?(123) # => 123 is not a symbol nor a string (TypeError) t[123] # => 123 is not a symbol nor a string (TypeError) ``` -- https://bugs.ruby-lang.org/