diff --git a/platform/core-impl/src/com/intellij/ide/plugins/PluginError.java b/platform/core-impl/src/com/intellij/ide/plugins/PluginError.java
index ef9b936bd592..0607d5c2aa60 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/PluginError.java
+++ b/platform/core-impl/src/com/intellij/ide/plugins/PluginError.java
@@ -2,21 +2,22 @@
 package com.intellij.ide.plugins;
 
 import com.intellij.openapi.extensions.PluginId;
+import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 final class PluginError {
   final IdeaPluginDescriptorImpl plugin;
-  private final String message;
-  private final String incompatibleReason;
-  private boolean myNotifyUser;
+  private final @Nls String message;
+  private final @Nls String incompatibleReason;
+  private final boolean myNotifyUser;
   private PluginId myDisabledDependency;
 
-  public PluginError(@Nullable IdeaPluginDescriptorImpl plugin, @NotNull String message, @Nullable String incompatibleReason) {
+  PluginError(@Nullable IdeaPluginDescriptorImpl plugin, @NotNull @Nls String message, @Nullable @Nls String incompatibleReason) {
     this(plugin, message, incompatibleReason, true);
   }
 
-  public PluginError(@Nullable IdeaPluginDescriptorImpl plugin,
+  PluginError(@Nullable IdeaPluginDescriptorImpl plugin,
                      @NotNull String message,
                      @Nullable String incompatibleReason,
                      boolean notifyUser) {
@@ -30,7 +31,7 @@ final class PluginError {
     myDisabledDependency = disabledDependency;
   }
 
-  @NotNull String toUserError() {
+  @NotNull @Nls String toUserError() {
     if (plugin == null) {
       return message;
     }
diff --git a/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java b/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java
index 67c476a619b2..057fbac67a89 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java
+++ b/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java
@@ -6,9 +6,7 @@ import com.intellij.openapi.util.BuildNumber;
 import com.intellij.openapi.util.io.FileUtil;
 import com.intellij.util.PlatformUtils;
 import com.intellij.util.text.VersionComparatorUtil;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.*;
 
 import java.nio.file.Path;
 import java.util.*;
@@ -100,7 +98,8 @@ final class PluginLoadingResult {
     }
   }
 
-  void reportIncompatiblePlugin(@NotNull IdeaPluginDescriptorImpl plugin, @NotNull String reason, @Nullable String since, @Nullable String until) {
+  void reportIncompatiblePlugin(@NotNull IdeaPluginDescriptorImpl plugin, @NotNull @Nls String reason, 
+                                @Nullable @NonNls String since, @Nullable @NonNls String until) {
     // do not report if some compatible plugin were already added
     // no race condition here — plugins from classpath are loaded before and not in parallel to loading from plugin dir
     if (idMap.containsKey(plugin.getPluginId())) {
diff --git a/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java b/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
index 8673aa0c3fca..b204be4c1cfc 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
+++ b/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
@@ -28,10 +28,7 @@ import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.execution.ParametersListUtil;
 import com.intellij.util.graph.*;
 import com.intellij.util.lang.UrlClassLoader;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-import org.jetbrains.annotations.TestOnly;
+import org.jetbrains.annotations.*;
 
 import java.io.*;
 import java.lang.invoke.MethodHandle;
@@ -1092,7 +1089,8 @@ public final class PluginManagerCore {
     return getIncompatibleMessage(buildNumber, descriptor.getSinceBuild(), descriptor.getUntilBuild()) != null;
   }
 
-  static @Nullable String getIncompatibleMessage(@NotNull BuildNumber buildNumber, @Nullable String sinceBuild, @Nullable String untilBuild) {
+  static @Nullable @Nls String getIncompatibleMessage(@NotNull BuildNumber buildNumber, @Nullable @NonNls String sinceBuild, 
+                                                      @Nullable @NonNls String untilBuild) {
     try {
       String message = null;
       BuildNumber sinceBuildNumber = sinceBuild == null ? null : BuildNumber.fromString(sinceBuild, null, null);