Self-hosted 2025 R2, instance under C:\Program Files\Acumatica ERP\xxxx. Publishing projects with Modern UI files fails. I confirmed the cause: the npm process runs under the app pool identity, which has no write permission inside C:\Program Files, so webpack dies instantly with no error at all. Switching the app pool from ApplicationPoolIdentity to LocalSystem fixes it. Granting Modify to the virtual account does not.
We publish only once or twice a year and we'd rather not create a dedicated service account on the OS. So what's the right way to handle this?
Switch to LocalSystem only during publish and switch back?
Reinstall the instance to a non-protected path like C:\Acumatica?
is there an official recommendation for the app pool identity and folder permissions when the instance is under C:\Program Files？
IIS app pool permissions break Modern UI publish — what's the recommended approach?
Hi
Yeah, I wouldn’t stick with LocalSystem on this one. It works, but it’s a lot more access than that pool needs, and flipping it before/after every publish is a pain you don’t want twice a year.
You’ve basically already figured out why it breaks. Program Files is locked down by Windows, so when webpack kicks off under the app pool account it just can’t write into the instance folder, and granting Modify doesn’t really take there since it’s not a normal folder.
The clean fix is to not run the instance out of Program Files at all. Acumatica actually says this in their customization guide - install to a path outside Program Files (they use something like C:\AcumaticaSites... as the example). So just redeploy the instance to something like C:\Acumatica, leave the app pool on the normal ApplicationPoolIdentity, and the Modern UI publish works with no fuss.
Move it off Program Files. That’s the supported setup, LocalSystem is just hiding the problem.
I hope this will help you as i also follow this.
Thanks.
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