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.

2026.3

IntelliJ Platform 2026.3

com.intellij.openapi.projectRoots.Sdk interface now extends com.intellij.openapi.util.UserDataHolderEx and inherits its abstract method putUserDataIfAbsent(@NotNull Key<T> key, @NotNull T value): Do not implement Sdk: it is a non-extendable interface.
com.intellij.openapi.projectRoots.Sdk interface now extends com.intellij.openapi.util.UserDataHolderEx and inherits its abstract method replace(@NotNull Key<T> key, @Nullable T oldValue, @Nullable T newValue): Do not implement Sdk: it is a non-extendable interface.

Kotlin UI DSL 1.0 Removal

Kotlin UI DSL Version 1 (the com.intellij.ui.layout DSL entry points) has been completely removed. Any access to the removed classes will lead to compilation or runtime errors. The migration should be done according to the Kotlin UI DSL Version 2 migration guide.

com.intellij.ui.layout.BaseBuilder class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.CCFlags class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.Cell class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.CellBuilder class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.CellMarker class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.LCFlags class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.LayoutBuilder class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.LayoutBuilderImpl class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.LayoutImplKt class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.LayoutKt class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.Row class removed: Migrate to Kotlin UI DSL Version 2.
com.intellij.ui.layout.RowBuilder class removed: Migrate to Kotlin UI DSL Version 2.

2026.2

IntelliJ Platform 2026.2

PolySymbols 2026.2

com.intellij.polySymbols.search.PsiSourcedPolySymbol class renamed to com.intellij.polySymbols.search.PsiLinkedPolySymbol: Use PsiLinkedPolySymbol instead. Additionally, the source property was renamed to linkedElement.
com.intellij.polySymbols.utils.PsiSourcedPolySymbolDelegate class renamed to com.intellij.polySymbols.utils.PsiLinkedPolySymbolDelegate: Use PsiLinkedPolySymbolDelegate instead.
com.intellij.polySymbols.refactoring.PsiSourcedPolySymbolRefactoringHelper class renamed to com.intellij.polySymbols.refactoring.PsiLinkedPolySymbolRefactoringHelper: Use PsiLinkedPolySymbolRefactoringHelper instead.
com.intellij.polySymbols.refactoring.PsiSourcedPolySymbolRenameHandler class renamed to com.intellij.polySymbols.refactoring.PsiLinkedPolySymbolRenameHandler: Use PsiLinkedPolySymbolRenameHandler instead.
com.intellij.polySymbols.search.PsiSourcedPolySymbolProvider class renamed to com.intellij.polySymbols.search.PsiLinkedPolySymbolProvider: Use PsiLinkedPolySymbolProvider instead.
com.intellij.polySymbols.search.PsiSourcedPolySymbolReference class renamed to com.intellij.polySymbols.search.PsiLinkedPolySymbolReference: Use PsiLinkedPolySymbolReference instead.
com.intellij.polySymbols.search.PsiSourcedPolySymbolReferenceSearcher class renamed to com.intellij.polySymbols.search.PsiLinkedPolySymbolReferenceSearcher: Use PsiLinkedPolySymbolReferenceSearcher instead.
com.intellij.polySymbols.search.PsiSourcedPolySymbolRequestResultProcessor class renamed to com.intellij.polySymbols.search.PsiLinkedPolySymbolRequestResultProcessor: Use PsiLinkedPolySymbolRequestResultProcessor instead.

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).

CLion 2026.2

The C/C++ language engine based on com.intellij.cidr.lang (CLion Classic) is no longer bundled with CLion. CLion Nova, based on the ReSharper C++ engine, is now the default and the only bundled C/C++ engine. The classic APIs remain available via the C/C++ Language Support via Classic Engine plugin (ID com.intellij.cidr.lang). Plugins depending on these APIs must declare a dependency on the Marketplace plugin using plugin("com.intellij.cidr.lang", "<version>"). See C/C++ Language Engine: Nova and Classic for setup details and CLion Nova API replacements.

com.jetbrains.cidr.lang.OCFileType class removed: The Classic C/C++ engine is no longer bundled. Depend on the C/C++ Language Support via Classic Engine plugin to keep using it, or migrate to com.jetbrains.rider.cpp.fileType.CppFileType (CLion Nova).
com.jetbrains.cidr.lang.OCLanguage class removed: The Classic C/C++ engine is no longer bundled. Depend on the C/C++ Language Support via Classic Engine plugin to keep using it, or migrate to com.jetbrains.rider.cpp.fileType.CppLanguage (CLion Nova).
com.jetbrains.cidr.lang.psi.OCFile class removed: Depend on the C/C++ Language Support via Classic Engine plugin to keep using it, or use com.jetbrains.rider.cpp.fileType.psi.CppFile (CLion Nova) for file-level access only.

CLion Nova has no frontend PSI, so the remaining com.jetbrains.cidr.lang classes — PSI, symbols, types, and resolve/references — have no replacement; depend on the Classic Engine plugin to keep using them.

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 {}.

Language Server Protocol (LSP) 2026.1.4

In 2026.1.4, key LSP classes were renamed. LspServerManager was renamed to LspClientManager and the service is registered only under the new interface. Plugins retrieving LspServerManager via project.service<LspServerManager>() or similar methods will get null. Use LspClientManager.getInstance(project) instead, or LspServerManager.getInstance(project) to support versions before 2026.4.1.

PolySymbols 2026.1

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.

20 July 2026