# Policy changes in CMake version 4.0.0

**URL:** https://discourse.cmake.org/t/policy-changes-in-cmake-version-4-0-0/13883
**Category:** Usage
**Created:** [April 4, 2025, 9:40am UTC](https://discourse.cmake.org/t/policy-changes-in-cmake-version-4-0-0/13883 "2025-04-04T09:40:47Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![fsimonis](https://discourse.cmake.org/user_avatar/discourse.cmake.org/fsimonis/32/1712_2.png) [@fsimonis](https://discourse.cmake.org/u/fsimonis)
#### Post date: [April 4, 2025, 9:40am UTC](https://discourse.cmake.org/t/policy-changes-in-cmake-version-4-0-0/13883/1 "2025-04-04T09:40:47Z")

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Hi,

The CMake release 4.0.0 removes the OLD behaviour of the policies CMP0000 to CMP0065.  
If you run into issues after the upgrade, this may be the reason why. Either directly or indirectly.

I had to manually grep the codebase to figure this out. Our CI exploded overnight due to MinGW and brew upgrading CMake to 4.0.0. It took us a while to figure out what was going on.  
A section in the CMake release notes regarding this would have been helpful.

Kind regards  
Frédéric

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### Author: ![ben.boeckel](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [April 4, 2025, 10:10am UTC](https://discourse.cmake.org/t/policy-changes-in-cmake-version-4-0-0/13883/2 "2025-04-04T10:10:22Z")

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It is mentioned in the release notes: [https://cmake.org/cmake/help/latest/release/4.0.html#deprecated-and-removed-features](https://cmake.org/cmake/help/latest/release/4.0.html#deprecated-and-removed-features), though the numbers are not given.

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### Author: ![LegalizeAdulthood](https://discourse.cmake.org/user_avatar/discourse.cmake.org/legalizeadulthood/32/5282_2.png) [@LegalizeAdulthood](https://discourse.cmake.org/u/LegalizeAdulthood)
#### Post date: [April 4, 2025, 2:45pm UTC](https://discourse.cmake.org/t/policy-changes-in-cmake-version-4-0-0/13883/3 "2025-04-04T14:45:24Z")

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IMO, it would be good to mention the minimum policy supported as it does for the minimum CMake version supported.

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### Author: ![LegalizeAdulthood](https://discourse.cmake.org/user_avatar/discourse.cmake.org/legalizeadulthood/32/5282_2.png) [@LegalizeAdulthood](https://discourse.cmake.org/u/LegalizeAdulthood)
#### Post date: [April 4, 2025, 2:47pm UTC](https://discourse.cmake.org/t/policy-changes-in-cmake-version-4-0-0/13883/4 "2025-04-04T14:47:23Z")

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I see that the policies page lists all the policies removed by CMake 4, so maybe just a link to the unsupported policies section?

[https://cmake.org/cmake/help/latest/manual/cmake-policies.7.html#unsupported-policies](https://cmake.org/cmake/help/latest/manual/cmake-policies.7.html#unsupported-policies)