diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackExportTask.java b/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackExportTask.java
index 5b99aa60c..1b56b8f1b 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackExportTask.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLModpackExportTask.java
@@ -25,6 +25,7 @@ import org.jackhuang.hmcl.util.gson.JsonUtils;
 import org.jackhuang.hmcl.util.io.Zipper;
 
 import java.io.File;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -75,7 +76,7 @@ public class HMCLModpackExportTask extends Task<Void> {
 
             Version mv = repository.getResolvedVersion(version);
             String gameVersion = GameVersion.minecraftVersion(repository.getVersionJar(version))
-                    .orElseThrow(() ->  new IllegalStateException("Cannot parse the version of " + version));
+                    .orElseThrow(() ->  new IOException("Cannot parse the version of " + version));
             zip.putTextFile(JsonUtils.GSON.toJson(mv.setJar(gameVersion)), "minecraft/pack.json"); // Making "jar" to gameVersion is to be compatible with old HMCL.
             zip.putTextFile(JsonUtils.GSON.toJson(modpack.setGameVersion(gameVersion)), "modpack.json"); // Newer HMCL only reads 'gameVersion' field.
         }
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java b/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java
index 88f458b75..816390e44 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/game/ModpackHelper.java
@@ -123,7 +123,7 @@ public final class ModpackHelper {
             return new MultiMCModpackInstallTask(profile.getDependency(), zipFile, modpack, ((MultiMCInstanceConfiguration) modpack.getManifest()), name)
                     .whenComplete(Schedulers.defaultScheduler(), success, failure)
                     .thenComposeAsync(new MultiMCInstallVersionSettingTask(profile, ((MultiMCInstanceConfiguration) modpack.getManifest()), name));
-        else throw new IllegalStateException("Unrecognized modpack: " + modpack);
+        else throw new IllegalArgumentException("Unrecognized modpack: " + modpack);
     }
 
     public static Task<Void> getUpdateTask(Profile profile, File zipFile, Charset charset, String name, ModpackConfiguration<?> configuration) throws UnsupportedModpackException, MismatchedModpackTypeException {
diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/ui/download/InstallerWizardProvider.java b/HMCL/src/main/java/org/jackhuang/hmcl/ui/download/InstallerWizardProvider.java
index 0c9208654..5aa2f2564 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/ui/download/InstallerWizardProvider.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/ui/download/InstallerWizardProvider.java
@@ -18,9 +18,11 @@
 package org.jackhuang.hmcl.ui.download;
 
 import javafx.scene.Node;
+import org.jackhuang.hmcl.download.DefaultDependencyManager;
 import org.jackhuang.hmcl.download.DownloadProvider;
 import org.jackhuang.hmcl.download.RemoteVersion;
 import org.jackhuang.hmcl.download.VersionMismatchException;
+import org.jackhuang.hmcl.download.fabric.FabricInstallTask;
 import org.jackhuang.hmcl.download.game.LibraryDownloadException;
 import org.jackhuang.hmcl.download.optifine.OptiFineInstallTask;
 import org.jackhuang.hmcl.game.Version;
@@ -114,9 +116,10 @@ public final class InstallerWizardProvider implements WizardProvider {
             } else {
                 Controllers.dialog(i18n("install.failed.downloading.detail", ((DownloadException) exception).getUrl()) + "\n" + StringUtils.getStackTrace(exception.getCause()), i18n("install.failed.downloading"), MessageType.ERROR, next);
             }
-        } else if (exception instanceof OptiFineInstallTask.UnsupportedOptiFineInstallationException) {
+        } else if (exception instanceof OptiFineInstallTask.UnsupportedOptiFineInstallationException ||
+                exception instanceof FabricInstallTask.UnsupportedFabricInstallationException) {
             Controllers.dialog(i18n("install.failed.optifine_conflict"), i18n("install.failed"), MessageType.ERROR, next);
-        } else if (exception instanceof UnsupportedOperationException) {
+        } else if (exception instanceof DefaultDependencyManager.UnsupportedLibraryInstallerException) {
             Controllers.dialog(i18n("install.failed.install_online"), i18n("install.failed"), MessageType.ERROR, next);
         } else if (exception instanceof VersionMismatchException) {
             VersionMismatchException e = ((VersionMismatchException) exception);
diff --git a/HMCL/src/main/resources/assets/lang/I18N.properties b/HMCL/src/main/resources/assets/lang/I18N.properties
index 4e750e6d5..7fea8ad54 100644
--- a/HMCL/src/main/resources/assets/lang/I18N.properties
+++ b/HMCL/src/main/resources/assets/lang/I18N.properties
@@ -132,7 +132,7 @@ install.failed.downloading=Failed to install due to some files not downloaded su
 install.failed.downloading.detail=Failed to download file: %s
 install.failed.downloading.timeout=Download timed out: %s
 install.failed.install_online=Unable to recognize what you provided installer file is
-install.failed.optifine_conflict=OptiFine and Forge are both installed simultaneously on Minecraft 1.13
+install.failed.optifine_conflict=Fabric, OptiFine and Forge are both installed simultaneously on Minecraft 1.13
 install.failed.version_mismatch=The library requires game version %s, but actual version is %s.
 install.installer.choose=Choose a %s version
 install.installer.fabric=Fabric
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/DefaultDependencyManager.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/DefaultDependencyManager.java
index 9debbf58c..dea2eacf3 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/DefaultDependencyManager.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/DefaultDependencyManager.java
@@ -94,7 +94,7 @@ public class DefaultDependencyManager extends AbstractDependencyManager {
         VersionList<?> versionList = getVersionList(libraryId);
         return versionList.loadAsync(gameVersion, getDownloadProvider())
                 .thenComposeAsync(() -> installLibraryAsync(baseVersion, versionList.getVersion(gameVersion, libraryVersion)
-                        .orElseThrow(() -> new IllegalStateException("Remote library " + libraryId + " has no version " + libraryVersion))));
+                        .orElseThrow(() -> new IOException("Remote library " + libraryId + " has no version " + libraryVersion))));
     }
 
     @Override
@@ -126,12 +126,15 @@ public class DefaultDependencyManager extends AbstractDependencyManager {
                     } catch (IOException ignore) {
                     }
 
-                    throw new UnsupportedOperationException("Library cannot be recognized");
+                    throw new UnsupportedLibraryInstallerException();
                 })
                 .thenApplyAsync(oldVersion::addPatch)
                 .thenComposeAsync(repository::save);
     }
 
+    public static class UnsupportedLibraryInstallerException extends Exception {
+    }
+
     /**
      * Remove installed library.
      * Will try to remove libraries and patches.
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/fabric/FabricInstallTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/fabric/FabricInstallTask.java
index 832065e76..bcce2df39 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/fabric/FabricInstallTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/fabric/FabricInstallTask.java
@@ -65,7 +65,7 @@ public final class FabricInstallTask extends Task<Version> {
     }
 
     @Override
-    public void preExecute() {
+    public void preExecute() throws Exception {
         if (!Objects.equals("net.minecraft.client.main.Main", version.resolve(dependencyManager.getGameRepository()).getMainClass()))
             throw new UnsupportedFabricInstallationException();
     }
@@ -128,6 +128,6 @@ public final class FabricInstallTask extends Task<Version> {
         return new Version("net.fabricmc", loaderVersion, 30000, arguments, mainClass, libraries);
     }
 
-    public static class UnsupportedFabricInstallationException extends UnsupportedOperationException {
+    public static class UnsupportedFabricInstallationException extends Exception {
     }
 }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/forge/ForgeNewInstallTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/forge/ForgeNewInstallTask.java
index 3b5eb6f92..16b71d71f 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/forge/ForgeNewInstallTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/forge/ForgeNewInstallTask.java
@@ -38,6 +38,7 @@ import org.jackhuang.hmcl.util.platform.OperatingSystem;
 import org.jackhuang.hmcl.util.platform.SystemUtils;
 
 import java.io.FileNotFoundException;
+import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
@@ -233,7 +234,7 @@ public class ForgeNewInstallTask extends Task<Version> {
                 List<String> args = processor.getArgs().stream().map(arg -> {
                     String parsed = parseLiteral(arg, data, ExceptionalFunction.identity());
                     if (parsed == null)
-                        throw new IllegalStateException("Invalid forge installation configuration");
+                        throw new IOException("Invalid forge installation configuration");
                     return parsed;
                 }).collect(Collectors.toList());
 
@@ -242,7 +243,7 @@ public class ForgeNewInstallTask extends Task<Version> {
                 LOG.info("Executing external processor " + processor.getJar().toString() + ", command line: " + new CommandBuilder().addAll(command).toString());
                 int exitCode = SystemUtils.callExternalProcess(command);
                 if (exitCode != 0)
-                    throw new IllegalStateException("Game processor exited abnormally");
+                    throw new IOException("Game processor exited abnormally");
 
                 for (Map.Entry<String, String> entry : outputs.entrySet()) {
                     Path artifact = Paths.get(entry.getKey());
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/VersionJsonDownloadTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/VersionJsonDownloadTask.java
index d165f96d5..4db5a45ac 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/VersionJsonDownloadTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/VersionJsonDownloadTask.java
@@ -24,6 +24,7 @@ import org.jackhuang.hmcl.task.GetTask;
 import org.jackhuang.hmcl.task.Task;
 import org.jackhuang.hmcl.util.io.NetworkUtils;
 
+import java.io.IOException;
 import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
@@ -61,9 +62,9 @@ public final class VersionJsonDownloadTask extends Task<String> {
     }
 
     @Override
-    public void execute() {
+    public void execute() throws IOException {
         RemoteVersion remoteVersion = gameVersionList.getVersion(gameVersion, gameVersion)
-                .orElseThrow(() -> new IllegalStateException("Cannot find specific version " + gameVersion + " in remote repository"));
+                .orElseThrow(() -> new IOException("Cannot find specific version " + gameVersion + " in remote repository"));
         String jsonURL = dependencyManager.getDownloadProvider().injectURL(remoteVersion.getUrl());
         dependencies.add(new GetTask(NetworkUtils.toURL(jsonURL)).storeTo(this::setResult));
     }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/optifine/OptiFineInstallTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/optifine/OptiFineInstallTask.java
index ba9ec6e7c..87be4a3f5 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/optifine/OptiFineInstallTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/optifine/OptiFineInstallTask.java
@@ -149,7 +149,7 @@ public final class OptiFineInstallTask extends Task<Version> {
                         gameRepository.getLibraryFile(version, optiFineLibrary).toString()
                 );
                 if (exitCode != 0)
-                    throw new IllegalStateException("OptiFine patcher failed");
+                    throw new IOException("OptiFine patcher failed");
             } else {
                 FileUtils.copyFile(dest, gameRepository.getLibraryFile(version, optiFineLibrary).toPath());
             }
@@ -188,7 +188,7 @@ public final class OptiFineInstallTask extends Task<Version> {
         dependencies.add(dependencyManager.checkLibraryCompletionAsync(getResult()));
     }
 
-    public static class UnsupportedOptiFineInstallationException extends UnsupportedOperationException {
+    public static class UnsupportedOptiFineInstallationException extends Exception {
     }
 
     /**
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventBus.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventBus.java
index 652194b4e..c74fa7330 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventBus.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventBus.java
@@ -20,6 +20,7 @@ package org.jackhuang.hmcl.event;
 import org.jackhuang.hmcl.util.Logging;
 
 import java.util.HashMap;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  *
@@ -27,12 +28,11 @@ import java.util.HashMap;
  */
 public final class EventBus {
 
-    private final HashMap<Class<?>, EventManager<?>> events = new HashMap<>();
+    private final ConcurrentHashMap<Class<?>, EventManager<?>> events = new ConcurrentHashMap<>();
 
     @SuppressWarnings("unchecked")
     public <T extends Event> EventManager<T> channel(Class<T> clazz) {
-        if (!events.containsKey(clazz))
-            events.put(clazz, new EventManager<>());
+        events.putIfAbsent(clazz, new EventManager<>());
         return (EventManager<T>) events.get(clazz);
     }
 
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventManager.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventManager.java
index f3963323c..7e12d96fb 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventManager.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/event/EventManager.java
@@ -22,6 +22,7 @@ import org.jackhuang.hmcl.util.SimpleMultimap;
 import java.lang.ref.WeakReference;
 import java.util.EnumMap;
 import java.util.HashSet;
+import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.function.Consumer;
 
 /**
@@ -31,7 +32,7 @@ import java.util.function.Consumer;
 public final class EventManager<T extends Event> {
 
     private final SimpleMultimap<EventPriority, Consumer<T>> handlers
-            = new SimpleMultimap<>(() -> new EnumMap<>(EventPriority.class), HashSet::new);
+            = new SimpleMultimap<>(() -> new EnumMap<>(EventPriority.class), CopyOnWriteArraySet::new);
 
     public Consumer<T> registerWeak(Consumer<T> consumer) {
         register(new WeakListener(consumer));
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/AssetObject.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/AssetObject.java
index 2a0b05725..00655b80e 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/AssetObject.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/AssetObject.java
@@ -54,6 +54,6 @@ public final class AssetObject implements Validation {
     @Override
     public void validate() throws JsonParseException {
         if (StringUtils.isBlank(hash) || hash.length() < 2)
-            throw new IllegalStateException("AssetObject hash cannot be blank.");
+            throw new JsonParseException("AssetObject hash cannot be blank.");
     }
 }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/World.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/World.java
index e71a406d0..f1a9809ea 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/World.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/World.java
@@ -91,7 +91,7 @@ public class World {
     private void loadFromZipImpl(Path root) throws IOException {
         Path levelDat = root.resolve("level.dat");
         if (!Files.exists(levelDat))
-            throw new IllegalArgumentException("Not a valid world zip file since level.dat cannot be found.");
+            throw new IOException("Not a valid world zip file since level.dat cannot be found.");
 
         getWorldName(levelDat);
     }
@@ -116,6 +116,9 @@ public class World {
         CompoundTag nbt = parseLevelDat(levelDat);
 
         CompoundTag data = nbt.get("Data");
+        if (data == null)
+            throw new IOException("level.dat missing Data");
+
         if (data.get("LevelName") instanceof StringTag)
             worldName = data.<StringTag>get("LevelName").getValue();
         else
@@ -209,7 +212,7 @@ public class World {
                 return Files.list(savesDir).flatMap(world -> {
                     try {
                         return Stream.of(new World(world));
-                    } catch (IOException | IllegalArgumentException e) {
+                    } catch (IOException e) {
                         Logging.LOG.log(Level.WARNING, "Failed to read world " + world, e);
                         return Stream.empty();
                     }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/multimc/MultiMCModpackExportTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/multimc/MultiMCModpackExportTask.java
index c2a72dfe7..3f35afa0e 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/multimc/MultiMCModpackExportTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/mod/multimc/MultiMCModpackExportTask.java
@@ -27,6 +27,7 @@ import org.jackhuang.hmcl.util.gson.JsonUtils;
 import org.jackhuang.hmcl.util.io.Zipper;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.StringWriter;
 import java.util.ArrayList;
 import java.util.List;
@@ -80,7 +81,7 @@ public class MultiMCModpackExportTask extends Task<Void> {
 
             LibraryAnalyzer analyzer = LibraryAnalyzer.analyze(repository.getResolvedPreservingPatchesVersion(versionId));
             String gameVersion = GameVersion.minecraftVersion(repository.getVersionJar(versionId))
-                    .orElseThrow(() ->  new IllegalStateException("Cannot parse the version of " + versionId));
+                    .orElseThrow(() -> new IOException("Cannot parse the version of " + versionId));
             List<MultiMCManifest.MultiMCManifestComponent> components = new ArrayList<>();
             components.add(new MultiMCManifest.MultiMCManifestComponent(true, false, "net.minecraft", gameVersion));
             analyzer.getVersion(FORGE).ifPresent(forgeVersion ->
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/task/FileDownloadTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/task/FileDownloadTask.java
index 8b3a7e9c7..7398f0345 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/task/FileDownloadTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/task/FileDownloadTask.java
@@ -292,7 +292,7 @@ public class FileDownloadTask extends Task<Void> {
                 }
 
                 if (downloaded != contentLength)
-                    throw new IllegalStateException("Unexpected file size: " + downloaded + ", expected: " + contentLength);
+                    throw new IOException("Unexpected file size: " + downloaded + ", expected: " + contentLength);
 
                 // Integrity check
                 if (integrityCheck != null) {
@@ -312,7 +312,7 @@ public class FileDownloadTask extends Task<Void> {
                 }
 
                 return;
-            } catch (IOException | IllegalStateException e) {
+            } catch (IOException e) {
                 if (temp != null)
                     temp.toFile().delete();
                 exception = e;
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/task/TaskExecutor.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/task/TaskExecutor.java
index 4c4d35047..9a29c199c 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/task/TaskExecutor.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/task/TaskExecutor.java
@@ -64,7 +64,7 @@ public final class TaskExecutor {
                         Logging.LOG.log(Level.WARNING, "An exception occurred in task execution", exception);
 
                         Throwable resolvedException = resolveException(exception);
-                        if (resolvedException instanceof RuntimeException) {
+                        if (resolvedException instanceof RuntimeException && !(resolvedException instanceof CancellationException)) {
                             // Track uncaught RuntimeException which are thrown mostly by our mistake
                             if (uncaughtExceptionHandler != null)
                                 uncaughtExceptionHandler.uncaughtException(Thread.currentThread(), resolvedException);