# How to build a sysimage for Windows
**URL:** https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500
**Category:** General Usage
**Tags:** question, package-compiler
**Created:** [July 27, 2026, 9:45pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500 "2026-07-27T21:45:21Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 27, 2026, 9:45pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/1 "2026-07-27T21:45:21Z")
I built a system image on Windows 10 using Julia 1.12. But I cannot start Julia with this system image:
```julia-auto
C:\Users\ufechner\repos\IM_AWES_bench.jl\bin>julia -J sysimage.dll
ERROR: could not load library "C:\Users\ufechner\repos\IM_AWES_bench.jl\bin\sysimage.dll"
%1 is not a valid Win32 application.
```
```julia-auto
julia> versioninfo()
Julia Version 1.12.6
Commit 15346901f0 (2026-04-09 19:20 UTC)
Build Info:
Official https://julialang.org release
Platform Info:
OS: Windows (x86_64-w64-mingw32)
CPU: 16 × AMD Ryzen 9 7950X 16-Core Processor
WORD_SIZE: 64
LLVM: libLLVM-18.1.7 (ORCJIT, znver4)
GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 16 virtual cores)
```
Any idea?
Works fine on Linux.
And yes, Windows and Julia are both 64 bit. So the error message is a bit confusing.
---
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 28, 2026, 5:20am UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/2 "2026-07-28T05:20:13Z")
Any ideas how to debug?
```bash
ufechner@ufryzen:~/Shared_Windows$ objdump -f sysimage.dll
sysimage.dll: file format pei-x86-64
architecture: i386:x86-64, flags 0x0000013b:
HAS_RELOC, EXEC_P, HAS_DEBUG, HAS_SYMS, HAS_LOCALS, D_PAGED
start address 0x00000003a4d61320
```
---
### Author:  [@mkitti](https://discourse.julialang.org/u/mkitti)
#### Post date: [July 29, 2026, 2:05am UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/3 "2026-07-29T02:05:38Z")
Hmm. My one thought is do you have a msys2 environment you could work with?
---
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 29, 2026, 1:32pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/4 "2026-07-29T13:32:46Z")
I tested on Windows 11 and got the same error.
You can reproduce the problem like this:
```julia-auto
git clone https://github.com/c-nicomar/IM_AWES_bench.jl.git
cd IM_AWES_bench.jl/bin
./install
./create_sys_image
cd ..
./bin/run_julia
```
Warning: Takes a long time.
---
### Author:  [@mkitti](https://discourse.julialang.org/u/mkitti)
#### Post date: [July 29, 2026, 3:10pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/5 "2026-07-29T15:10:06Z")
> [@ufechner7](#):
>
> ```julia-auto
> %1 is not a valid Win32 application.
>
> ```
If this is your main lead, then we need to create a Windows debugging environment. There are two paths, one is to use MSYS2 and use a GCC-based framework to analyze dynamic library loading.
There are also tools like WinDbg:
> **[Install WinDbg - Windows drivers](https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/)**
>
> Start here for an overview on the Windows debugger and installing WinDbg.
Essentially, we need to do the eqiuvalent of `LD_DEBUG=libs`. You’ll need to use gflags.exe that should come with WinDbg to enable logging of shared library loading on the Julia executable.
PackageCompiler.jl does require a C compiler, and I’m not sure which one you are using.
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [July 29, 2026, 3:33pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/6 "2026-07-29T15:33:16Z")
How big is the sysimage?
---
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 29, 2026, 5:08pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/7 "2026-07-29T17:08:49Z")
> [@mkitti](#):
>
> [PackageCompiler.jl](https://juliaregistries.github.io/General/packages/redirect_to_repo/PackageCompiler) does require a C compiler, and I’m not sure which one you are using.
How shall I know that? I think PackageCompiler installs its own compiler as an artifact. One of the machines where I tried compiling it is quite virgin, not much on it, definitely no C compiler that I installed myself. I just installed Git for Windows, which comes with a Bash shell.
And a few months ago, this all worked fine.
---
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 30, 2026, 8:35pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/8 "2026-07-30T20:35:00Z")
> [@kristoffer.carlsson](#):
>
> How big is the sysimage?
```julia-auto
ufechner@ufryzen:~/Shared_Windows$ ls -la sysimage.dll
-rwxrwxr-x 1 ufechner ufechner 2208050613 Jul 27 23:21 sysimage.dll
ufechner@ufryzen:~/Shared_Windows$ ls -lah sysimage.dll
-rwxrwxr-x 1 ufechner ufechner 2.1G Jul 27 23:21 sysimage.dll
```
```julia-auto
const PACKAGES = [
"ModelingToolkit",
"OrdinaryDiffEq",
"MakieControlPlots",
"CSV",
"DataFrames",
]
```
Is that too big?
---
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 31, 2026, 6:31pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/9 "2026-07-31T18:31:11Z")
Removing ModelingToolkit from the system image solved the problem:
This works:
```julia-auto
const PACKAGES = [
"OrdinaryDiffEq",
"MakieControlPlots",
"CSV",
"DataFrames",
]
```
Size now:
```julia-auto
ufechner@DESKTOP-USD9U6B MINGW64 ~/repos/InductionMachineDrives.jl/bin
$ ls -la sysimage.dll
-rwxr-xr-x 1 ufechner 197121 1733065543 Jul 31 20:04 sysimage.dll*
$ ls -lah sysimage.dll
-rwxr-xr-x 1 ufechner 197121 1.7G Jul 31 20:04 sysimage.dll*
```
This looks a bit as if there might be an upper limit of 2 GB on the size of the sysimage on Windows. If that should be the case, PackageCompiler should at least print a warning.
Any comments? Could this be fixed?
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [July 31, 2026, 7:59pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/10 "2026-07-31T19:59:05Z")
> [@ufechner7](#):
>
> Is that too big?
Yes, limit is 2 GB
> [@ufechner7](#):
>
> This looks a bit as if there might be an upper limit of 2 GB on the size of the sysimage on Windows. If that should be the case, PackageCompiler should at least print a warning.
That’s a good idea. [Add compression option and warn on too big sysimage sizes on windows - Pull Request #1114 - JuliaLang/PackageCompiler.jl - GitHub](https://github.com/JuliaLang/PackageCompiler.jl/pull/1114) should warn and also on 1.13 add the compress option that significantly reduces the size of the sysimage (but makes it slightly slower to load).
---
### Author:  [@ufechner7](https://discourse.julialang.org/u/ufechner7)
#### Post date: [July 31, 2026, 8:13pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/11 "2026-07-31T20:13:41Z")
Is there also such a size limit on macOS, or is it only on Windows?
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [July 31, 2026, 8:19pm UTC](https://discourse.julialang.org/t/how-to-build-a-sysimage-for-windows/138500/12 "2026-07-31T20:19:04Z")
There could be something around 4GB for those but I am not 100% sure