# Having Problem When installing utop in ocaml 4.06 **URL:** \ **Category:** Ecosystem\ **Tags:** utop\ **Created:** [November 11, 2017, 10:06am UTC](https://discuss.ocaml.org/t/having-problem-when-installing-utop-in-ocaml-4-06/1102 "2017-11-11T10:06:38Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Jonathan\_Kashongwe](https://avatars.discourse-cdn.com/v4/letter/j/f04885/32.png) [@Jonathan\_Kashongwe](https://discuss.ocaml.org/u/Jonathan_Kashongwe)\ **Post date:** [November 11, 2017, 10:06am UTC](https://discuss.ocaml.org/t/having-problem-when-installing-utop-in-ocaml-4-06/1102/1 "2017-11-11T10:06:38Z")
Hi, i’m new to Ocaml and When i try to install utop, i got this error : #=== ERROR while installing zed.1.5 ===========================================# # opam-version 1.2.2 # os darwin # command jbuilder build -p zed -j 4 # path /Users/jonakash/.opam/4.06.0/build/zed.1.5 # compiler 4.06.0 # exit-code 1 # env-file /Users/jonakash/.opam/4.06.0/build/zed.1.5/zed-10970-6d07ae.env # stdout-file /Users/jonakash/.opam/4.06.0/build/zed.1.5/zed-10970-6d07ae.out # stderr-file /Users/jonakash/.opam/4.06.0/build/zed.1.5/zed-10970-6d07ae.err ### stderr # Error: This expression has type bytes but an expression was expected of type # […] # (cd \_build/default && /Users/jonakash/.opam/4.06.0/bin/ocamlc.opt -w -40 -g -bin-annot -I /Users/jonakash/.opam/4.06.0/lib/bytes -I /Users/jonakash/.opam/4.06.0/lib/camomile -I /Users/jonakash/.opam/4.06.0/lib/ocaml -I /Users/jonakash/.opam/4.06.0/lib/react -no-alias-deps -I src -o src/zed\_rope.cmo -c -impl src/zed\_rope.ml) # File “src/zed\_rope.ml”, line 541, characters 13-91: # Error: This expression has type bytes but an expression was expected of type # Zed\_utf8.t = string # ocamlopt src/zed\_utf8.{cmx,o} (exit 2) # (cd \_build/default && /Users/jonakash/.opam/4.06.0/bin/ocamlopt.opt -w -40 -g -I /Users/jonakash/.opam/4.06.0/lib/bytes -I /Users/jonakash/.opam/4.06.0/lib/camomile -I /Users/jonakash/.opam/4.06.0/lib/ocaml -I /Users/jonakash/.opam/4.06.0/lib/react -no-alias-deps -I src -o src/zed\_utf8.cmx -c -impl src/zed\_utf8.ml) # File “src/zed\_utf8.ml”, line 303, characters 26-29: # Error: This expression has type bytes but an expression was expected of type # string Help Me please, ---
**Author:** ![dbuenzli](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dbuenzli/32/18_2.png) [@dbuenzli](https://discuss.ocaml.org/u/dbuenzli)\ **Post date:** [November 11, 2017, 11:42am UTC](https://discuss.ocaml.org/t/having-problem-when-installing-utop-in-ocaml-4-06/1102/2 "2017-11-11T11:42:16Z")
In the just released `4.06` version of OCaml strings became immutable by default. Not all the packages had the time to update yet. If you are new to OCaml I suggest sticking to 4.05 for the time being. ---
**Author:** ![perry](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/perry/32/518_2.png) [@perry](https://discuss.ocaml.org/u/perry)\ **Post date:** [November 11, 2017, 2:01pm UTC](https://discuss.ocaml.org/t/having-problem-when-installing-utop-in-ocaml-4-06/1102/3 "2017-11-11T14:01:49Z")
That said, after the latest package updates, I can now build utop under 4.06. (It was broken before that.) I suspect that the original poster should probably do `opam update` and it might then be possible to build it. ---
**Author:** ![Jonathan\_Kashongwe](https://avatars.discourse-cdn.com/v4/letter/j/f04885/32.png) [@Jonathan\_Kashongwe](https://discuss.ocaml.org/u/Jonathan_Kashongwe)\ **Post date:** [November 11, 2017, 10:01pm UTC](https://discuss.ocaml.org/t/having-problem-when-installing-utop-in-ocaml-4-06/1102/4 "2017-11-11T22:01:02Z")
Thanks for your answer, i just do opam update, try again and utop built successful. ---
**Author:** ![perry](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/perry/32/518_2.png) [@perry](https://discuss.ocaml.org/u/perry)\ **Post date:** [November 11, 2017, 10:03pm UTC](https://discuss.ocaml.org/t/having-problem-when-installing-utop-in-ocaml-4-06/1102/5 "2017-11-11T22:03:01Z")
FYI, @dbuenzli is correct. Even though utop is now working, there are still a number of packages that don’t quite work on 4.06 yet. You may be happiest doing 4.05 for the moment.