Incompatible Changes in IntelliJ Platform and Plugins API 2026.*

Please see Verifying Plugin Compatibility on how to use Plugin Verifier and IDE inspections to check such problems.

Early Access Program (EAP) releases of upcoming versions are available here.

2026.1

IntelliJ Platform 2026.1

AWT input event handlers no longer run under write-intent lock: Custom input handlers (KeyListener, MouseAdapter, etc.) no longer execute under the write-intent lock. If PSI or other write-intent-protected data needs to be accessed in these handlers, explicitly acquire a read action using ReadAction.nonBlocking().submit() or coroutine-based equivalents such as readAction {}.

PolySymbols

com.intellij.polySymbols.PolySymbol.getOrigin() method removed

The property was confusing and in many cases was not used. Its functionality is replaced by:

framework property - provide com.intellij.polySymbols.html.HtmlFrameworkSymbolsSupport.HtmlFrameworkIdProperty value through PolySymbol.Property mechanism

defaultIcon property - implement icon property and return true for PolySymbol.DocHideIconProperty through PolySymbol.Property mechanism

typeSupport property - provide com.intellij.polySymbols.utils.PolySymbolTypeSupport.TypeSupportProperty value through PolySymbol.Property mechanism

com.intellij.polySymbols.PolySymbolQualifiedKind class renamed to com.intellij.polySymbols.PolySymbolKind

additionally name property was renamed to kindName and qualifiedKind properties and parameters across the package were renamed to kind

The following classes no longer implement PsiModificationTracker (this requirement was confusing):

Implementing PsiModificationTracker was replaced by modificationTracker property for the following classes:

Java Plugin 2026.1

The Java plugin has been split into several modules with their own classloaders. This shouldn't affect plugins that use standard <depends>com.intellij.java</depends> dependency. If a plugin depends on specific Java plugin modules directly, the dependencies should be updated to reference the new module names.

2026.2

Kotlin Plugin 2026.2

K1 Plugin Removal

K1 Plugin was completely removed from the distribution. Any access to its classes or to the classes of the K1 Compiler Frontend would lead to runtime errors. The migration should be done according to the migration guide.

org.jetbrains.kotlin.asJava.classes.KtLightClassForSourceDeclaration class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.asJava.classes.KtLightClassImpl class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.asJava.classes.KtUltraLightClass class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.asJava.elements.KtLightMemberImpl class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.asJava.elements.KtLightPsiLiteral class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.actions.generate.KotlinGenerateMemberActionBase class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.base.projectStructure.moduleInfo.ModuleSourceInfo class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.base.utils.fqname.FqNameUtilKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.project.MultiplatformUtilKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.util.JavaResolutionUtils class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.codeInsight.DescriptorToSourceUtilsIde class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.codeInsight.KtFunctionPsiElementCellRenderer class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.codeInsight.ReferenceVariantsHelper class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.codeInsight.postfix.KtPostfixTemplateProviderKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.core.ShortenReferences class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.core.UtilsKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.core.overrideImplement.GenerateMembersHandler class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.core.overrideImplement.GenerateMembersHandler.Companion class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.core.overrideImplement.ImplementMembersHandler class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.core.overrideImplement.OverrideMemberChooserObject class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.gradleJava.compilerPlugin.AbstractCompilerPluginGradleImportHandler class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.imports.ImportsUtils class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.inspections.IntentionBasedInspectionKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.quickfix.KotlinIntentionActionsFactory class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.quickfix.KotlinQuickFixAction class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.quickfix.KotlinSingleIntentionActionFactory class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.quickfix.QuickFixContributor class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.quickfix.QuickFixes class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.quickfix.createFromUsage.CreateFromUsageFixBase class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.KotlinRefactoringUtilKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.changeSignature.ChangeSignatureUtilsKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.changeSignature.KotlinChangeInfo class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.changeSignature.KotlinChangeSignatureData class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.changeSignature.KotlinMethodDescriptor class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.memberInfo.MemberInfoUtilsKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.refactoring.safeDelete.KotlinSafeDeleteProcessor class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.search.usagesSearch.SearchHelpersKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.search.usagesSearch.UtilsKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.CallTypeAndReceiver class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.IdeDescriptorRenderers class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.ImportInsertHelper class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.ImportInsertHelper.Companion class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.ModifierListModifactorKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.TypeUtils class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.j2k.UtilsKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.resolve.lazy.BodyResolveMode class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.util.DescriptorUtilsKt class removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.asJava.KotlinAsJavaSupport.getLightClass(KtClassOrObject) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.analyze$default(KtElement, BodyResolveMode, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.analyze(KtElement, BodyResolveMode) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.getResolutionFacade(KtElement) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveImportReference(KtFile, FqName) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveToCall$default(KtElement, BodyResolveMode, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveToDescriptorIfAny$default(KtClassOrObject, BodyResolveMode, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveToDescriptorIfAny$default(KtDeclaration, BodyResolveMode, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveToDescriptorIfAny$default(KtNamedFunction, BodyResolveMode, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveToDescriptorIfAny$default(KtProperty, BodyResolveMode, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.caches.resolve.ResolutionUtils.resolveToDescriptorIfAny(KtDeclaration, BodyResolveMode) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.idea.util.CommentSaver.restore$default(CommentSaver, PsiElement, boolean, int, Object) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.js.descriptorUtils.DescriptorUtilsKt.getJetTypeFqName(KotlinType, boolean) method removed: Migrate to K2 (Analysis API).
org.jetbrains.kotlin.js.descriptorUtils.DescriptorUtilsKt.getNameIfStandardType(KotlinType) method removed: Migrate to K2 (Analysis API).

18 June 2026