# Installation issue pymc3 and pymcexperimental
**URL:** https://discourse.pymc.io/t/installation-issue-pymc3-and-pymcexperimental/12397
**Category:** version agnostic
**Tags:** arviz, installation
**Created:** [June 28, 2023, 3:25pm UTC](https://discourse.pymc.io/t/installation-issue-pymc3-and-pymcexperimental/12397 "2023-06-28T15:25:02Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@alok](https://discourse.pymc.io/u/alok)
#### Post date: [June 28, 2023, 3:25pm UTC](https://discourse.pymc.io/t/installation-issue-pymc3-and-pymcexperimental/12397/1 "2023-06-28T15:25:02Z")
I am trying to install pymc3 and pymcexperimental. When I first install pymc3 and then pymcexperimental, I get the following error.
ERROR: pip’s dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
pymc3 3.11.5 requires scipy\<1.8.0,\>=1.7.3, but you have scipy 1.11.0 which is incompatible.
When I first install pymcexperimental and then pymc3, I get the following error.
ERROR: pip’s dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
pymc 5.5.0 requires arviz\>=0.13.0, but you have arviz 0.12.1 which is incompatible.
I am trying to install it in Mac.
Thank you very much in advance!
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### Author:  [@ricardoV94](https://discourse.pymc.io/u/ricardoV94)
#### Post date: [June 28, 2023, 3:28pm UTC](https://discourse.pymc.io/t/installation-issue-pymc3-and-pymcexperimental/12397/2 "2023-06-28T15:28:26Z")
pymc-experimental requires `pymc>5.0`, you can’t use the old `pymc3`
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### Author:  [@alok](https://discourse.pymc.io/u/alok)
#### Post date: [June 29, 2023, 2:23pm UTC](https://discourse.pymc.io/t/installation-issue-pymc3-and-pymcexperimental/12397/3 "2023-06-29T14:23:19Z")
Thanks. It is working now.