I'm trying to run a local instance of tzscan: https://gitlab.com/tzscan/tzscan But I'm not 100% sure about how to fix the following errors:

Error log:

File "./libs/ez-api/libs/ez-api/ezEncodingJS.ml", line 80, characters 26-32:
Error: Unbound module Js

rule 644: target ./_obuild/ez-api-js/ezEncodingJS.cmo not built

File "./libs/base58-blockies/base58Blockies.ml", line 82, characters 7-32:
Error (warning 3): deprecated: module Tyxml_js
Will be removed past 2019-04-01. Use Js_of_ocaml_tyxml.Tyxml_js instead.

rule 625: target ./_obuild/base58-blockies/base58Blockies.cmi not built
rule 625: target ./_obuild/base58-blockies/base58Blockies.cmo not built
Makefile:44: recipe for target 'all' failed

Is there anyone that can help, or is there more info I need to post to be able to?

2 Answers 2


Your problem is related to the dependency js_of_ocaml. Some backward incompatibilities have been introduced in the API of the last versions (3.3.0 and 3.4.0).

Try to manually downgrade by doing opam install js_of_ocaml.3.2.0 js_of_ocaml-compiler.3.2.0 js_of_ocaml-lwt.3.2.0 js_of_ocaml-tyxml.3.2.0 js_of_ocaml-ppx.3.2.0, "clean up" everything and retry to build...


No unfortunately the last release on http://gitlab.com/tzscan/tzscan is only compatible with js_of_ocaml.3.4.0, it will not work with 3.3.0 or 3.2.0. So there must a problem in your switch. Could you provide us with the result of opam list?

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