# Fable 5.0.0-rc.4 released!

**URL:** <https://forum.devtalk.com/t/fable-5-0-0-rc-4-released/238265>\
**Category:** Frontend Official News\
**Tags:** newsbot, fable, official-news\
**Created:** [19 March 2026 19:19 UTC](https://forum.devtalk.com/t/fable-5-0-0-rc-4-released/238265 "2026-03-19T19:19:14Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![NewsBot](https://forum.devtalk.com/user_avatar/forum.devtalk.com/newsbot/32/1114_2.png) [@NewsBot](https://forum.devtalk.com/u/NewsBot)\
**Post date:** [19 March 2026 19:19 UTC](https://forum.devtalk.com/t/fable-5-0-0-rc-4-released/238265/1 "2026-03-19T19:19:14Z")

</div>

[Fable](https://devtalk.com/fable) 5.0.0-rc.4 has been released.

> [@](#):
>
> ### Fixed
> 
> - [JS/TS] Fix `Array.zeroCreate` producing `null` for user-defined struct (value type) elements instead of a default-initialized instance (by @MangelMaxime)
> - [All] Fix interpolated string holes missing format specifiers in State.fs and Python/Replacements.fs (code scanning alerts 1144, 1145, 1512)
> - [Rust] Replace unsafe `.IsSome && .Value` option pattern with `Option.exists` in Fable2Rust.fs (code scanning alert 1125)
> - [JS/TS] Fix `Unchecked.defaultof<char>` being emitted as `null` instead of `'\0'` (by @MangelMaxime)
> - [JS/TS] Fix `static val mutable` fields declared with `[<DefaultValue>]` not being zero-initialized (fix #2739) (by @MangelMaxime)
> - [JS/TS/Python] Fix record/struct types augmented with `static let` or `static member val` generating extra constructor parameters for each static field, causing constructor arguments to be assigned to wrong slots (by @MangelMaxime)
> - [TS] Annotate `System.Collections.Generic.IList<T>` as `MutableArray<T>` (by @MangelMaxime)
> - [JS/TS] Fix `ResizeArray` index getter/setter not throwing `IndexOutOfRangeException` when index is out of bounds (fix #3812) (by @MangelMaxime)
> - [Beam] Fix unused term warning in try/catch when exception variable is not referenced (by @dbrattli)
> - [Beam] Fix “no effect” warning for pure BIF calls (`self/0`, `node/0`) in non-final block positions (by @dbrattli)
> - [Beam] Fix `reraise()` generating unbound `MatchValue` variable — use raw Erlang reason variable for re-throw (by @dbrattli)
> - [Beam] Fix `Erlang.receive<'T>()` resolving to timeout overload due to F# unit argument (by @dbrattli)
> - [JS/TS] Generate comments for members in class decorated with `[<AttachMembers>]` (by @MangelMaxime)
> - [Beam] Fix `[<ImportAll>]` generating invalid `module:*()` Erlang code when binding is used as a value (by @dbrattli)
> - [Beam] Fix string slicing and `Substring` with compound expressions producing wrong `binary:part` length due to missing parentheses in emitted Erlang (by @dbrattli)
> - [Beam] …

Link: [Release 5.0.0-rc.4 · fable-compiler/Fable · GitHub](https://github.com/fable-compiler/Fable/releases/tag/5.0.0-rc.4)