# Want to move to 1.5, but lots of "compiled by prerelease" errors

**URL:** <https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499>\
**Category:** Support\
**Created:** [April 10, 2021, 10:50pm UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499 "2021-04-10T22:50:14Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![benjaminhill](https://avatars.discourse-cdn.com/v4/letter/b/57b2e6/32.png) [@benjaminhill](https://discuss.kotlinlang.org/u/benjaminhill)\
**Post date:** [April 10, 2021, 10:50pm UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499/1 "2021-04-10T22:50:14Z")

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I’d like to start using 1.5. Maven.

```auto
    <properties>
        <kotlin.compiler.jvmTarget>11</kotlin.compiler.jvmTarget>
        <kotlin.compiler.incremental>true</kotlin.compiler.incremental>
        <kotlin.version>1.5.0-M2</kotlin.version>
        <kotlin.coroutine.version>1.4.3</kotlin.coroutine.version>
    </properties>

```

But I get a ton of  
`Class 'kotlin.Unit' is compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler`

Without any compile args, I get  
`Kotlin: Pre-release classes were found in dependencies. Remove them from the classpath, recompile with a release compiler or use '-Xskip-prerelease-check' to suppress errors`

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**Author:** ![darksnake](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/darksnake/32/2479_2.png) [@darksnake](https://discuss.kotlinlang.org/u/darksnake)\
**Post date:** [April 11, 2021, 7:19am UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499/2 "2021-04-11T07:19:41Z")

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The problem is that Idea 2021.1 still does not have Kotlin 1.5 plugin. The compilation itself goes fine (at least in Gradle). I think you should just ignore those errors for now, roll back idea if they do bother you and enable this ‘-Xskip-prerelease-check’ if maven does not allow to compile without it.

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**Author:** ![Loke](https://avatars.discourse-cdn.com/v4/letter/l/c68b51/32.png) [@Loke](https://discuss.kotlinlang.org/u/Loke)\
**Post date:** [April 11, 2021, 4:43pm UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499/3 "2021-04-11T16:43:16Z")

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One can always download the prerelease version of the Kotlin plugin. The documentation on how to do so is found here: [Install the EAP Plugin for IntelliJ IDEA or Android Studio | Kotlin](https://kotlinlang.org/docs/install-eap-plugin.html)

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**Author:** ![darksnake](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/darksnake/32/2479_2.png) [@darksnake](https://discuss.kotlinlang.org/u/darksnake)\
**Post date:** [April 11, 2021, 5:17pm UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499/4 "2021-04-11T17:17:54Z")

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There is no EAP 1.5 version for IDEA 2021.1. So for now downgrading the idea itself is the only solution. But I think the 1.5 plugin will come soon.

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**Author:** ![Loke](https://avatars.discourse-cdn.com/v4/letter/l/c68b51/32.png) [@Loke](https://discuss.kotlinlang.org/u/Loke)\
**Post date:** [April 12, 2021, 2:14pm UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499/5 "2021-04-12T14:14:54Z")

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Well, I’m using 2021.1 with 1.5. I do recall getting the errors reported above, but I got rid of them by going into settings, kotlin, update channel and selecting 1.5.

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**Author:** ![benjaminhill](https://avatars.discourse-cdn.com/v4/letter/b/57b2e6/32.png) [@benjaminhill](https://discuss.kotlinlang.org/u/benjaminhill)\
**Post date:** [May 19, 2021, 6:05am UTC](https://discuss.kotlinlang.org/t/want-to-move-to-1-5-but-lots-of-compiled-by-prerelease-errors/21499/6 "2021-05-19T06:05:58Z")

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This is all working fine now.