Error:java: error: release version 15 not supported

Hi,

I also receive the same error after update to version 2020.1.1

See https://youtrack.jetbrains.com/issue/IDEA-240068 .

Change JDK_X to JDK_14 in .idea/misc.xml.

Well, this worked for me. thanks Serge Baranov

right click on project + select language level then change and apply :)

Same issue after upgrading to IntelliJ 2021.1, so to reiterate:

change this line in .idea\misc.xml:

<component name="ProjectRootManager" version="2" languageLevel="JDK_X" default="true" project-jdk-name="16" project-jdk-type="JavaSDK">

to a valid JDK value, such as:

<component name="ProjectRootManager" version="2" languageLevel="JDK_16" default="true" project-jdk-name="16" project-jdk-type="JavaSDK">

Ideally, the error message should be more helpful, such as:

error: JDK_X language level not supported in misc.xml

If you are going to force your customers to manually repair your product by hacking one of the .xml files, you should at least give us the maximum amount of information necessary to fix the issue.

Hello Frederick, 

Can you please describe the issue in more details. What build of IntelliJ IDEA do you have? What type of project do you have and what error is shown for you? Are JDK and language level correctly defined in Project Structure | Project (SDK, language level), Project Structure | Modules (language level) and in Preferences | Build, Execution, Deployment | Compiler | Java Compiler? 

Thank you 

I opened a previously created project that ran normally in the last version of 2020 (2020.3?), but as soon as I opened it in IntelliJ 2021.1 and tried to Build it, the error previously described appeared.

After an exhaustive internet search, I discovered that the only way to fix this issue is to MANUALLY HACK the .idea/misc.xml file and change languageLevel="JDK_X" to languageLevel="JDK_16"  (or other valid value).

No amount of poking around in the myriad (bewildering is more like it) "settings" could fix this issue.

Don't bother with any further responses.  Consider this closed via "manual hack of misc.xml". 

P.S. My research shows this has been an issue in IntelliJ for years, so at least now I have the "hack tool" in my "toolbelt" ready to fix this issue the next time it appears (and history shows that it is a matter of WHEN not IF it will appear).

Happened to me with version 2021.1.1 CE and none of the above hacks helped.

Removing the .idea folder in the project root folder and then reimporting the project solved the issue. 

Nothing working for me. I'm on

IntelliJ IDEA 2021.2.1 (Ultimate Edition)
Build #IU-212.5080.55, built on August 23, 2021
Licensed to Thomas Hehl
Subscription is active until February 8, 2022.
Runtime version: 11.0.11+9-b1504.16 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Linux 5.11.0-31-generic
GC: ParNew, ConcurrentMarkSweep
Memory: 1931M
Cores: 16
Registry: external.system.substitute.library.dependencies=true
Non-Bundled Plugins: IdeaVIM (0.69), ideanginx9 (0.1.9), net.sjrx.intellij.plugins.systemdunitfiles (0.3.3), org.exbin.deltahex.intellij (0.2.4), com.haulmont.jpab (4.5-212)
Kotlin: 212-1.5.10-release-IJ5080.55
Current Desktop: ubuntu:GNOME

Please share your project files (.idea directory and *.iml) at https://uploads.jetbrains.com.

When I went back into my production version of IntelliJ, I got an error telling me gradle JVM wasn't set. I set this and restarted my RC version, and the problem was resolved...

I am having the same issue with Java 17. I have Zulu 17 installed, I checked all the settings mentioned, changed the setting in pom.xml, checked Project settings, module settings, Java Compiler settings, misc.xml, and yet I'm still getting this issue.

Upload id: 2021_09_27_Sw6VjwAz9zahasT8 (file: project-files.zip)

Hello Peter,

In the provided archive there is only an *.iml file. If possible can you please create an issue at YouTrack: https://youtrack.jetbrains.com/issues/IDEA

and attach the project sample to it. Thank you 

Created https://youtrack.jetbrains.com/issue/IDEA-279071

Thank you