This is previously posted at https://discourse.julialang.org/t/strange-bug-segmentation-fault-11-solely-existed-in-julia-v1-0/21392 . It seems that no one would help with this. I know it's quite difficult for it seems to be reproduced only if a project depends on both DataFrames.jl and MLStyle.jl . CI: https://travis-ci.org/queryverse/Query.jl/jobs/500796102 codes: https://github.com/thautwarm/Query.jl/tree/12a1d3c214f42bb63bd18aaa936f127798d74f46