Copilot Chat Stopped working in JetBrains Rider 2025.2

[prplecake]

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Bug

Copilot Feature Area

JetBrains & Xcode

Body

Completions work fine, chat doesn't. Chat gets stuck on "Initializing Copilot". Except now mine is stuck thinking I'm logged out, where the extension is very clearly authenticated. (Green check mark)

Clicking the "Sign in for Github Copilot" button signs me out the first time, then goes through the login device flow the second time.

Disabling/re-enabling the extension didn't help. Reinstalling the extension without signing out brings me back to where I was an hour ago, Initializing Copilot.

This error seems relevant:

2025-08-21 11:23:08,653 [  23866] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - Unhandled exception in [CoroutineName(PreconditionsService), Dispatchers.Default]
java.lang.NoClassDefFoundError: org/jetbrains/kotlin/idea/base/util/UiUtils
	at com.github.copilot.agent.edit.input.CopilotEditInputPanel.<init>(CopilotEditInputPanel.kt:170)
	at com.github.copilot.agent.edit.session.component.EditSessionComponent.<init>(EditSessionComponent.kt:51)
	at com.github.copilot.agent.edit.session.component.EditSessionComponent.<init>(EditSessionComponent.kt:43)
	at com.github.copilot.agent.edit.session.EditSessionController.<init>(EditSessionController.kt:31)
	at com.github.copilot.agent.edit.session.EditSessionController.<init>(EditSessionController.kt:20)
	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSessionController(EditSessionManager.kt:194)
	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSessionController$default(EditSessionManager.kt:192)
	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSession(EditSessionManager.kt:181)
	at com.github.copilot.agent.edit.session.EditSessionManager.getOrCreateEditSession(EditSessionManager.kt:170)
	at com.github.copilot.agent.edit.session.EditSessionManager.<init>(EditSessionManager.kt:48)
	at com.github.copilot.agent.edit.session.EditSessionManager.<init>(EditSessionManager.kt:28)
	at com.github.copilot.chat.window.CopilotChatToolWindow.onCopilotReady(CopilotChatToolWindow.kt:267)
	at com.github.copilot.chat.window.CopilotChatToolWindow.access$onCopilotReady(CopilotChatToolWindow.kt:64)
	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invokeSuspend(CopilotChatToolWindow.kt:245)
	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invoke(CopilotChatToolWindow.kt)
	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invoke(CopilotChatToolWindow.kt)
	at com.github.copilot.chat.precondition.PreconditionsService$refreshPreconditions$1.invokeSuspend(ChatPreconditionsService.kt:80)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.internal.ScopeCoroutine.afterResume(Scopes.kt:36)
	at kotlinx.coroutines.AbstractCoroutine.resumeWith(AbstractCoroutine.kt:101)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:46)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:613)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:1189)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:778)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:765)

Full error

2025-08-21 11:46:40,675 [  30812] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - Unhandled exception in [CoroutineName(PreconditionsService), Dispatchers.Default]
java.lang.NoClassDefFoundError: org/jetbrains/kotlin/idea/base/util/UiUtils
	at com.github.copilot.agent.edit.input.CopilotEditInputPanel.<init>(CopilotEditInputPanel.kt:170)
	at com.github.copilot.agent.edit.session.component.EditSessionComponent.<init>(EditSessionComponent.kt:51)
	at com.github.copilot.agent.edit.session.component.EditSessionComponent.<init>(EditSessionComponent.kt:43)
	at com.github.copilot.agent.edit.session.EditSessionController.<init>(EditSessionController.kt:31)
	at com.github.copilot.agent.edit.session.EditSessionController.<init>(EditSessionController.kt:20)
	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSessionController(EditSessionManager.kt:194)
	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSessionController$default(EditSessionManager.kt:192)
	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSession(EditSessionManager.kt:181)
	at com.github.copilot.agent.edit.session.EditSessionManager.getOrCreateEditSession(EditSessionManager.kt:170)
	at com.github.copilot.agent.edit.session.EditSessionManager.<init>(EditSessionManager.kt:48)
	at com.github.copilot.agent.edit.session.EditSessionManager.<init>(EditSessionManager.kt:28)
	at com.github.copilot.chat.window.CopilotChatToolWindow.onCopilotReady(CopilotChatToolWindow.kt:267)
	at com.github.copilot.chat.window.CopilotChatToolWindow.access$onCopilotReady(CopilotChatToolWindow.kt:64)
	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invokeSuspend(CopilotChatToolWindow.kt:245)
	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invoke(CopilotChatToolWindow.kt)
	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invoke(CopilotChatToolWindow.kt)
	at com.github.copilot.chat.precondition.PreconditionsService$refreshPreconditions$1.invokeSuspend(ChatPreconditionsService.kt:80)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.internal.ScopeCoroutine.afterResume(Scopes.kt:36)
	at kotlinx.coroutines.AbstractCoroutine.resumeWith(AbstractCoroutine.kt:101)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:46)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:613)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:1189)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:778)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:765)
Caused by: java.lang.ClassNotFoundException: org.jetbrains.kotlin.idea.base.util.UiUtils PluginClassLoader(plugin=PluginMainDescriptor(name=GitHub Copilot, id=com.github.copilot, version=1.5.53.12241-243-nightly, isBundled=false, path=~\AppData\Roaming\JetBrains\Rider2025.2\plugins\github-copilot-intellij), packagePrefix=null, state=active, parents=ContentModuleDescriptor(moduleName=intellij.vcs.github.tracker, package=org.jetbrains.plugins.github.tasks) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.json, package=org.jetbrains.plugins.github.json) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.git/terminal, package=git4idea.terminal, descriptorPath=intellij.vcs.git.terminal.xml) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.git/newUiOnboarding, package=git4idea.newUiOnboarding, descriptorPath=intellij.vcs.git.newUiOnboarding.xml) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.github.ultimate.docker, package=com.intellij.vcs.github.ultimate.docker) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.ultimate.cron, package=com.intellij.vcs.github.ultimate.cron) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.ultimate.features, package=com.intellij.vcs.github.ultimate) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.git.frontend, package=com.intellij.vcs.git.frontend) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.git.coverage, package=com.intellij.vcs.git.coverage) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.relaxng) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.vcs.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.vcs.log.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.spellchecker) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.spellchecker.xml) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.tasks) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.tasks.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.vcs.dvcs.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.collaborationTools) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.vcs.git.shared, loadingRule=EMBEDDED) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.github, loadingRule=EMBEDDED) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.git) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.git/localHistory, descriptorPath=intellij.vcs.git.localHistory.xml) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), PluginMainDescriptor(name=IdeaVim, id=IdeaVIM, version=2.27.1, isBundled=false, path=~\AppData\Roaming\JetBrains\Rider2025.2\plugins\IdeaVIM), PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), )
	at com.intellij.ide.plugins.cl.PluginClassLoader.loadClass(PluginClassLoader.kt:159)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
	... 26 more
2025-08-21 11:46:40,676 [  30813] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - JetBrains Rider 2025.2.0.1  Build #RD-252.23892.537
2025-08-21 11:46:40,676 [  30813] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - JDK: 21.0.7; VM: OpenJDK 64-Bit Server VM; Vendor: JetBrains s.r.o.
2025-08-21 11:46:40,676 [  30813] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - OS: Windows 11
2025-08-21 11:46:40,676 [  30813] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - Plugin to blame: GitHub Copilot version: 1.5.53.12241-243-nightly
2025-08-21 11:46:40,676 [  30813] SEVERE - #c.i.o.a.i.CoroutineExceptionHandlerImpl - Last Action: 
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - Exception in thread "DefaultDispatcher-worker-16" java.lang.NoClassDefFoundError: org/jetbrains/kotlin/idea/base/util/UiUtils
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.input.CopilotEditInputPanel.<init>(CopilotEditInputPanel.kt:170)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.component.EditSessionComponent.<init>(EditSessionComponent.kt:51)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.component.EditSessionComponent.<init>(EditSessionComponent.kt:43)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionController.<init>(EditSessionController.kt:31)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionController.<init>(EditSessionController.kt:20)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSessionController(EditSessionManager.kt:194)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSessionController$default(EditSessionManager.kt:192)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionManager.newEditSession(EditSessionManager.kt:181)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionManager.getOrCreateEditSession(EditSessionManager.kt:170)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionManager.<init>(EditSessionManager.kt:48)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.agent.edit.session.EditSessionManager.<init>(EditSessionManager.kt:28)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.chat.window.CopilotChatToolWindow.onCopilotReady(CopilotChatToolWindow.kt:267)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.chat.window.CopilotChatToolWindow.access$onCopilotReady(CopilotChatToolWindow.kt:64)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invokeSuspend(CopilotChatToolWindow.kt:245)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invoke(CopilotChatToolWindow.kt)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.chat.window.CopilotChatToolWindow$subscribeToAuthStatus$1$1.invoke(CopilotChatToolWindow.kt)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.github.copilot.chat.precondition.PreconditionsService$refreshPreconditions$1.invokeSuspend(ChatPreconditionsService.kt:80)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.internal.ScopeCoroutine.afterResume(Scopes.kt:36)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.AbstractCoroutine.resumeWith(AbstractCoroutine.kt:101)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:46)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:613)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:1189)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:778)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:765)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [CoroutineName(PreconditionsService), StandaloneCoroutine{Cancelling}@6bdf54b9, Dispatchers.Default]
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - Caused by: java.lang.ClassNotFoundException: org.jetbrains.kotlin.idea.base.util.UiUtils PluginClassLoader(plugin=PluginMainDescriptor(name=GitHub Copilot, id=com.github.copilot, version=1.5.53.12241-243-nightly, isBundled=false, path=~\AppData\Roaming\JetBrains\Rider2025.2\plugins\github-copilot-intellij), packagePrefix=null, state=active, parents=ContentModuleDescriptor(moduleName=intellij.vcs.github.tracker, package=org.jetbrains.plugins.github.tasks) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.json, package=org.jetbrains.plugins.github.json) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.git/terminal, package=git4idea.terminal, descriptorPath=intellij.vcs.git.terminal.xml) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.git/newUiOnboarding, package=git4idea.newUiOnboarding, descriptorPath=intellij.vcs.git.newUiOnboarding.xml) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.github.ultimate.docker, package=com.intellij.vcs.github.ultimate.docker) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.ultimate.cron, package=com.intellij.vcs.github.ultimate.cron) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.ultimate.features, package=com.intellij.vcs.github.ultimate) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.git.frontend, package=com.intellij.vcs.git.frontend) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.git.coverage, package=com.intellij.vcs.git.coverage) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.relaxng) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.vcs.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.vcs.log.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.spellchecker) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.spellchecker.xml) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.tasks) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.tasks.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.vcs.dvcs.impl) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.platform.collaborationTools) <- PluginMainDescriptor(name=IDEA CORE, id=com.intellij, version=252.23892.537, isBundled=true, path=~\AppData\Local\Programs\Rider\lib), ContentModuleDescriptor(moduleName=intellij.vcs.git.shared, loadingRule=EMBEDDED) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), ContentModuleDescriptor(moduleName=intellij.vcs.github, loadingRule=EMBEDDED) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.github.git) <- PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), ContentModuleDescriptor(moduleName=intellij.vcs.git/localHistory, descriptorPath=intellij.vcs.git.localHistory.xml) <- PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), PluginMainDescriptor(name=Git, id=Git4Idea, version=252.23892.537, package=git4idea, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-git), PluginMainDescriptor(name=IdeaVim, id=IdeaVIM, version=2.27.1, isBundled=false, path=~\AppData\Roaming\JetBrains\Rider2025.2\plugins\IdeaVIM), PluginMainDescriptor(name=GitHub, id=org.jetbrains.plugins.github, version=252.23892.537-IU, isBundled=true, path=~\AppData\Local\Programs\Rider\plugins\vcs-github-IU), )
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at com.intellij.ide.plugins.cl.PluginClassLoader.loadClass(PluginClassLoader.kt:159)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
2025-08-21 11:46:40,681 [  30818]   INFO - STDERR - 	... 26 more

Edit, forgot to mention this is with Github CoPilot plugin v1.5.53.12241-243-nightly

Update: Doesn't seem to work in 2025.1 anymore either! Sweet, great job, team!

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[prplecake]

Github used to be good.

[AntGalanin06]

Hello 👋

The problem is caused by an incompatibility between the nightly version of the GitHub Copilot plugin (v1.5.53.12241-243-nightly) and your version of JetBrains Rider.
The error java.lang.NoClassDefFoundError: org/jetbrains/kotlin/idea/base/util/UiUtils directly indicates that the plugin is trying to call a class that is missing in your IDE's environment.
This is a common issue when using unstable (nightly) builds.

---

Solution: Install the Stable Version of the Plugin

The most reliable way to fix this is to uninstall the nightly version and install the latest stable version of GitHub Copilot from the JetBrains Marketplace.

Step-by-step instructions

1. Uninstall the current plugin

   • Open your IDE settings: File → Settings... (or Ctrl+Alt+S).
   • Go to the Plugins section.
   • On the Installed tab, find GitHub Copilot.
   • Click Uninstall.

2. Restart the IDE
   This is an important step to completely remove all plugin files.

3. Install the stable version

   • Open File → Settings... → Plugins again.
   • Go to the Marketplace tab.
   • In the search bar, type GitHub Copilot.
   • Find the official plugin by GitHub and click Install.
   • Make sure the name does not include "nightly".

4. Restart the IDE again
   A restart will be required after installing the new plugin.

5. Log in
   After restarting, log in to your GitHub Copilot account.
   The chat issue should now be resolved.

---

If the Problem Persists

• Invalidate IDE Caches
  Sometimes, issues can be caused by a corrupted cache.

  • Go to the menu File → Invalidate Caches....
  • In the dialog box, check the box for Clear file system cache and Local History and click Invalidate and Restart.

• Check for Updates
  Ensure you have the latest version of JetBrains Rider installed, as plugins often depend on updates to the IDE itself.

---

Using the stable version of the plugin will almost certainly solve this problem, as it is compiled against dependencies that are guaranteed to be present in the release version of the IDE.

[prplecake]

I think this AI answer failed to consider the fact that JetBrains removed that class, and that no previous versions of the plugin will work. I'm not testing all that to figure it out.

[prplecake]

In fact this suggestion is just wrong. There are no other version of the Github CoPilot extension in the JetBrains Marketplace.

[MarcoDroll]

You can download the latest stable version her:
https://plugins.jetbrains.com/plugin/17718-github-copilot/versions/stable
and install it from disk.
Dont forget to disable auto-update.

[mecodeatlas]

Hi @AntGalanin06,

We’ve clarified our stance on using generative AI tools like ChatGPT within our Community via this announcement. Please review the guidelines to ensure your post meets them as failure to adhere to those rules can result in action taken by our moderator team.  You can read our updated Code of Conduct and the announcement for more details. Thank you for helping us maintain an authentic and beneficial space for everyone.