diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccount.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccount.java
index 1274b1733..b02ef7e70 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccount.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccount.java
@@ -20,10 +20,7 @@ package org.jackhuang.hmcl.auth.offline;
 import org.jackhuang.hmcl.auth.Account;
 import org.jackhuang.hmcl.auth.AuthInfo;
 import org.jackhuang.hmcl.auth.AuthenticationException;
-import org.jackhuang.hmcl.util.Lang;
-import org.jackhuang.hmcl.util.Pair;
-import org.jackhuang.hmcl.util.StringUtils;
-import org.jackhuang.hmcl.util.UUIDTypeAdapter;
+import org.jackhuang.hmcl.util.*;
 
 import java.util.Map;
 import java.util.Objects;
@@ -66,7 +63,7 @@ public class OfflineAccount extends Account {
 
     @Override
     public AuthInfo logIn() throws AuthenticationException {
-        if (StringUtils.isBlank(username) || StringUtils.isBlank(uuid))
+        if (StringUtils.isBlank(username))
             throw new AuthenticationException("Username cannot be empty");
 
         return new AuthInfo(username, uuid, uuid);
@@ -107,6 +104,9 @@ public class OfflineAccount extends Account {
 
     @Override
     public String toString() {
-        return "OfflineAccount[username=" + username + ", uuid=" + uuid + "]";
+        return new ToStringBuilder(this)
+                .append("username", username)
+                .append("uuid", uuid)
+                .toString();
     }
 }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccountFactory.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccountFactory.java
index 49b8dd47d..35290a887 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccountFactory.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/OfflineAccountFactory.java
@@ -21,9 +21,13 @@ import org.jackhuang.hmcl.auth.AccountFactory;
 import org.jackhuang.hmcl.auth.CharacterSelector;
 import org.jackhuang.hmcl.util.DigestUtils;
 import org.jackhuang.hmcl.util.Lang;
+import org.jackhuang.hmcl.util.Logging;
+import org.jackhuang.hmcl.util.UUIDTypeAdapter;
 
 import java.net.Proxy;
 import java.util.Map;
+import java.util.UUID;
+import java.util.logging.Level;
 
 /**
  *
@@ -46,6 +50,9 @@ public class OfflineAccountFactory extends AccountFactory<OfflineAccount> {
                 .orElseThrow(() -> new IllegalStateException("Offline account configuration malformed."));
         String uuid = Lang.get(storage, "uuid", String.class)
                 .orElse(getUUIDFromUserName(username));
+        
+        // Check if the uuid is vaild
+        UUIDTypeAdapter.fromString(uuid);
 
         return new OfflineAccount(username, uuid);
     }