# JLD2 CodecLz4 compression stopped working

**URL:** <https://discourse.julialang.org/t/jld2-codeclz4-compression-stopped-working/132249>\
**Category:** General Usage\
**Tags:** jld2, lz4, data-compression\
**Created:** [September 10, 2025, 12:58pm UTC](https://discourse.julialang.org/t/jld2-codeclz4-compression-stopped-working/132249 "2025-09-10T12:58:59Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ju\_ska](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Ju\_ska](https://discourse.julialang.org/u/Ju_ska)\
**Post date:** [September 10, 2025, 12:58pm UTC](https://discourse.julialang.org/t/jld2-codeclz4-compression-stopped-working/132249/1 "2025-09-10T12:58:59Z")

</div>

Hi,

all of a sudden, compressing a Jld2 with Lz4 throws an error:

```julia-auto
using JLD2
using CodecLz4

name = rand(10)
detail = rand(10)
values = rand(10)

jldopen("./test.jdl2", "w"; compress = LZ4FrameCompressor()) do f
                        f["name"] = name 
                        f["detail"] = detail
                        f["values"] = values            
                    end

ERROR: ArgumentError: Failed to interpret the compression argument.
Stacktrace:
 [1] normalize_filters(compress::LZ4FrameCompressor)
   @ JLD2.Filters ~/.julia/packages/JLD2/WDhXU/src/Filters.jl:161
 [2] jldopen(fname::String, wr::Bool, create::Bool, truncate::Bool, iotype::Type{…}; fallback::Type{…}, compress::LZ4FrameCompressor, mmaparrays::Bool, typemap::Function, parallel_read::Bool, plain::Bool)
   @ JLD2 ~/.julia/packages/JLD2/WDhXU/src/JLD2.jl:185
 [3] jldopen(fname::String, mode::String; iotype::Type, kwargs::@Kwargs{compress::LZ4FrameCompressor})
   @ JLD2 ~/.julia/packages/JLD2/WDhXU/src/JLD2.jl:297
 [4] jldopen(::Function, ::String, ::Vararg{String}; kws::@Kwargs{compress::LZ4FrameCompressor})
   @ JLD2 ~/.julia/packages/JLD2/WDhXU/src/loadsave.jl:2
 [5] top-level scope
   @ REPL[10]:1
Some type information was truncated. Use `show(err)` to see complete types.

```

It used to work like one month ago.  
My packages are up-to-date.

---

<div class="post-metadata">

**Author:** ![Ju\_ska](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Ju\_ska](https://discourse.julialang.org/u/Ju_ska)\
**Post date:** [September 10, 2025, 1:02pm UTC](https://discourse.julialang.org/t/jld2-codeclz4-compression-stopped-working/132249/2 "2025-09-10T13:02:41Z")

</div>

Maybe there’s an upstream change:

> **[Compression · Julia Data Format](https://juliaio.github.io/JLD2.jl/stable/compression/)**
>
> Documentation for Julia Data Format.

I added this to the previous code:

```julia-auto
using JLD2Lz4

jldopen("./test.jdl2", "w"; compress = Lz4Filter()) do f
                        f["name"] = name
                        f["detail"] = detail
                        f["values"] = values
                    end

```

Looks like the compression is working now, but I didn’t try yet to read the archive.

---

<div class="post-metadata">

**Author:** ![Ju\_ska](https://avatars.discourse-cdn.com/v4/letter/j/ecd19e/32.png) [@Ju\_ska](https://discourse.julialang.org/u/Ju_ska)\
**Post date:** [September 10, 2025, 1:07pm UTC](https://discourse.julialang.org/t/jld2-codeclz4-compression-stopped-working/132249/3 "2025-09-10T13:07:37Z")

</div>

Seems ok:

```julia-auto
julia> JLD2.load("./test.jdl2")
Dict{String, Any} with 3 entries:
  "name" => [0.212438, 0.174893, 0.846498, 0.326715, 0.131913, 0.87852, 0.118283, 0.165016, 0.816943, 0.969886]
  "values" => [0.643116, 0.362288, 0.354138, 0.86716, 0.112778, 0.121993, 0.696981, 0.825894, 0.859359, 0.1539]
  "detail" => [0.874008, 0.511029, 0.0107484, 0.721257, 0.741567, 0.664445, 0.237355, 0.506097, 0.60906, 0.644165]

```