diff --git a/Backend/Backend/Controllers/IssuesController.cs b/Backend/Backend/Controllers/IssuesController.cs
index c22b831..64c38d0 100644
--- a/Backend/Backend/Controllers/IssuesController.cs
+++ b/Backend/Backend/Controllers/IssuesController.cs
@@ -108,39 +108,39 @@ public async Task<IActionResult> SubmitQuest(long id)
         quest.CompletedAt = DateTime.UtcNow;
 
         var user = await _context.Users.FindAsync(userId);
-        if (user != null)
-        {
-            user.ExperiencePoints += issue.XPReward;
+        if (user == null)
+            return NotFound("User account not found.");
+
+        user.ExperiencePoints += issue.XPReward;
 
-            // Update streak based on contribution dates (once per day)
-            var today = DateTime.UtcNow.Date;
-            if (user.LastContributionDate.HasValue)
+        // Update streak based on contribution dates (once per day)
+        var today = DateTime.UtcNow.Date;
+        if (user.LastContributionDate.HasValue)
+        {
+            var lastDate = user.LastContributionDate.Value.Date;
+            if (lastDate == today)
+            {
+                // Already contributed today – do not increment streak
+            }
+            else if (lastDate == today.AddDays(-1))
             {
-                var lastDate = user.LastContributionDate.Value.Date;
-                if (lastDate == today)
-                {
-                    // Already contributed today – do not increment streak
-                }
-                else if (lastDate == today.AddDays(-1))
-                {
-                    // Contributed yesterday – extend streak
-                    user.CurrentStreak += 1;
-                }
-                else
-                {
-                    // Gap in contributions – reset streak
-                    user.CurrentStreak = 1;
-                }
+                // Contributed yesterday – extend streak
+                user.CurrentStreak += 1;
             }
             else
             {
+                // Gap in contributions – reset streak
                 user.CurrentStreak = 1;
             }
-
-            user.LastContributionDate = DateTime.UtcNow;
         }
+        else
+        {
+            user.CurrentStreak = 1;
+        }
+
+        user.LastContributionDate = DateTime.UtcNow;
 
         await _context.SaveChangesAsync();
-        return Ok(new { message = $"{issue.XPReward} XP Awarded!", totalXp = user?.ExperiencePoints });
+        return Ok(new { message = $"{issue.XPReward} XP Awarded!", totalXp = user.ExperiencePoints });
     }
 }
\ No newline at end of file
diff --git a/Backend/Backend/Migrations/20260315082912_InitialCreate.Designer.cs b/Backend/Backend/Migrations/20260315082912_InitialCreate.Designer.cs
index 503f37e..5d41354 100644
--- a/Backend/Backend/Migrations/20260315082912_InitialCreate.Designer.cs
+++ b/Backend/Backend/Migrations/20260315082912_InitialCreate.Designer.cs
@@ -125,7 +125,7 @@ protected override void BuildTargetModel(ModelBuilder modelBuilder)
 
                     b.Property<string>("GitHubId")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasColumnType("nvarchar(450)");
 
                     b.Property<string>("GitHubUsername")
                         .IsRequired()
@@ -136,6 +136,9 @@ protected override void BuildTargetModel(ModelBuilder modelBuilder)
 
                     b.HasKey("Id");
 
+                    b.HasIndex("GitHubId")
+                        .IsUnique();
+
                     b.HasIndex("GitHubUsername")
                         .IsUnique();
 
diff --git a/Backend/Backend/Migrations/20260315082912_InitialCreate.cs b/Backend/Backend/Migrations/20260315082912_InitialCreate.cs
index e6e829f..9b406ba 100644
--- a/Backend/Backend/Migrations/20260315082912_InitialCreate.cs
+++ b/Backend/Backend/Migrations/20260315082912_InitialCreate.cs
@@ -55,7 +55,7 @@ protected override void Up(MigrationBuilder migrationBuilder)
                 columns: table => new
                 {
                     Id = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
-                    GitHubId = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    GitHubId = table.Column<string>(type: "nvarchar(450)", nullable: false),
                     GitHubUsername = table.Column<string>(type: "nvarchar(450)", nullable: false),
                     Email = table.Column<string>(type: "nvarchar(max)", nullable: true),
                     AvatarUrl = table.Column<string>(type: "nvarchar(max)", nullable: true),
@@ -111,6 +111,12 @@ protected override void Up(MigrationBuilder migrationBuilder)
                 column: "GitHubIssueId",
                 unique: true);
 
+            migrationBuilder.CreateIndex(
+                name: "IX_Users_GitHubId",
+                table: "Users",
+                column: "GitHubId",
+                unique: true);
+
             migrationBuilder.CreateIndex(
                 name: "IX_Users_GitHubUsername",
                 table: "Users",
diff --git a/Backend/Backend/Migrations/20260315125659_AddUniqueConstraints.cs b/Backend/Backend/Migrations/20260315125659_AddUniqueConstraints.cs
index 4f15c30..687b757 100644
--- a/Backend/Backend/Migrations/20260315125659_AddUniqueConstraints.cs
+++ b/Backend/Backend/Migrations/20260315125659_AddUniqueConstraints.cs
@@ -14,14 +14,6 @@ protected override void Up(MigrationBuilder migrationBuilder)
                 name: "IX_Quests_UserId",
                 table: "Quests");
 
-            migrationBuilder.AlterColumn<string>(
-                name: "GitHubId",
-                table: "Users",
-                type: "nvarchar(450)",
-                nullable: false,
-                oldClrType: typeof(string),
-                oldType: "nvarchar(max)");
-
             migrationBuilder.AlterColumn<string>(
                 name: "Status",
                 table: "Quests",
@@ -30,12 +22,6 @@ protected override void Up(MigrationBuilder migrationBuilder)
                 oldClrType: typeof(string),
                 oldType: "nvarchar(max)");
 
-            migrationBuilder.CreateIndex(
-                name: "IX_Users_GitHubId",
-                table: "Users",
-                column: "GitHubId",
-                unique: true);
-
             migrationBuilder.CreateIndex(
                 name: "IX_Quests_UserId_GitHubIssueId_ActiveStatus",
                 table: "Quests",
@@ -47,22 +33,10 @@ protected override void Up(MigrationBuilder migrationBuilder)
         /// <inheritdoc />
         protected override void Down(MigrationBuilder migrationBuilder)
         {
-            migrationBuilder.DropIndex(
-                name: "IX_Users_GitHubId",
-                table: "Users");
-
             migrationBuilder.DropIndex(
                 name: "IX_Quests_UserId_GitHubIssueId_ActiveStatus",
                 table: "Quests");
 
-            migrationBuilder.AlterColumn<string>(
-                name: "GitHubId",
-                table: "Users",
-                type: "nvarchar(max)",
-                nullable: false,
-                oldClrType: typeof(string),
-                oldType: "nvarchar(450)");
-
             migrationBuilder.AlterColumn<string>(
                 name: "Status",
                 table: "Quests",
diff --git a/Backend/Backend/Program.cs b/Backend/Backend/Program.cs
index cb3098c..28761fa 100644
--- a/Backend/Backend/Program.cs
+++ b/Backend/Backend/Program.cs
@@ -52,7 +52,7 @@
 var secretKey = jwtSettings["Key"];
 if (string.IsNullOrEmpty(secretKey))
     throw new InvalidOperationException("JwtSettings:Key is not configured. Set it via environment variable or user secrets.");
-var key = Encoding.ASCII.GetBytes(secretKey);
+var key = Encoding.UTF8.GetBytes(secretKey);
 
 builder.Services.AddAuthentication(options =>
 {