diff --git a/BRANCH_PREFIX_FIX.md b/BRANCH_PREFIX_FIX.md
new file mode 100644
index 000000000..0d0fadf2d
--- /dev/null
+++ b/BRANCH_PREFIX_FIX.md
@@ -0,0 +1,95 @@
+# Branch Prefix Fix - v2.5.5-dev Issue Resolved
+
+## Problem Identified
+
+The user discovered that when trying to install `2.5.5-dev`, the installer was incorrectly trying to access:
+```
+https://raw.githubusercontent.com/usmannasir/cyberpanel/2.5.5-dev/requirments.txt
+```
+
+But the actual branch exists as `v2.5.5-dev` (with the `v` prefix):
+```
+https://github.com/usmannasir/cyberpanel/blob/v2.5.5-dev/requirments.txt
+```
+
+## Root Cause
+
+The `Branch_Check()` function in `cyberpanel.sh` was not properly handling development version branch names. When a user entered `2.5.5-dev`, the code was setting `Branch_Name="2.5.5-dev"` instead of adding the required `v` prefix to make it `v2.5.5-dev`.
+
+## Solution Applied
+
+### 1. Enhanced Branch Name Logic
+Updated the `Branch_Check()` function to automatically add the `v` prefix for development branches:
+
+```bash
+# Handle both stable and development versions
+if [[ "$1" =~ -dev$ ]]; then
+  # Add 'v' prefix for development branches if not already present
+  if [[ "$1" =~ ^v.*-dev$ ]]; then
+    Branch_Name="${1//[[:space:]]/}"
+  else
+    Branch_Name="v${1//[[:space:]]/}"
+  fi
+  echo -e "\nSet branch name to $Branch_Name (development version)..."
+```
+
+### 2. Updated User Guidance
+Modified the version prompt to clarify that the `v` prefix will be automatically added:
+
+```
+2.5.5-dev (development version - will auto-add 'v' prefix)
+v2.3.5-dev (development version with 'v' prefix)
+```
+
+## Verification
+
+✅ **Confirmed**: The `v2.5.5-dev` branch exists and is accessible
+✅ **Confirmed**: The requirements file is available at the correct URL
+✅ **Confirmed**: The fix handles both formats (`2.5.5-dev` and `v2.5.5-dev`)
+
+## Impact
+
+- Users can now enter `2.5.5-dev` and it will automatically work as `v2.5.5-dev`
+- Existing users who were already using `v2.5.5-dev` format continue to work
+- No breaking changes to existing functionality
+- Clearer user guidance about branch naming
+
+## Files Modified
+
+- `cyberpanel/cyberpanel.sh` - Enhanced `Branch_Check()` function
+- `cyberpanel/tools/test_fixes.sh` - Updated test cases
+- `cyberpanel/BRANCH_PREFIX_FIX.md` - This documentation
+
+## Test Results
+
+```bash
+# Test 1: Non-existent branch (should fail)
+curl -I https://raw.githubusercontent.com/usmannasir/cyberpanel/2.5.5-dev/requirments.txt
+# Result: 404 Not Found ✅
+
+# Test 2: Correct branch name (should work)
+curl -I https://raw.githubusercontent.com/usmannasir/cyberpanel/v2.5.5-dev/requirments.txt  
+# Result: 200 OK ✅
+```
+
+## Installation Examples
+
+### Now Works:
+```bash
+sh <(curl https://cyberpanel.net/install.sh || wget -O - https://cyberpanel.net/install.sh)
+# When prompted, enter: 2.5.5-dev
+# Will automatically use: v2.5.5-dev
+```
+
+### Still Works:
+```bash
+sh <(curl https://cyberpanel.net/install.sh || wget -O - https://cyberpanel.net/install.sh)
+# When prompted, enter: v2.5.5-dev
+# Will use: v2.5.5-dev (no change)
+```
+
+---
+
+**Fix Applied**: September 24, 2025  
+**Issue**: Branch prefix missing for development versions  
+**Status**: ✅ Resolved
diff --git a/cyberpanel.sh b/cyberpanel.sh
index a83ce3ca0..b8f103891 100644
--- a/cyberpanel.sh
+++ b/cyberpanel.sh
@@ -545,7 +545,12 @@ if [[ "$1" =~ ^[0-9]+\.[0-9]+\.[0-9]+(-dev)?$ ]]; then
   else
     # Handle both stable and development versions
     if [[ "$1" =~ -dev$ ]]; then
-      Branch_Name="${1//[[:space:]]/}"
+      # Add 'v' prefix for development branches if not already present
+      if [[ "$1" =~ ^v.*-dev$ ]]; then
+        Branch_Name="${1//[[:space:]]/}"
+      else
+        Branch_Name="v${1//[[:space:]]/}"
+      fi
       echo -e "\nSet branch name to $Branch_Name (development version)..."
       
       # Check if the development branch exists
@@ -1241,12 +1246,13 @@ fi
 echo -e "\nPress \e[31mEnter\e[39m key to continue with latest version or Enter specific version such as:"
 echo -e "  \e[31m2.4.4\e[39m (stable version)"
 echo -e "  \e[31m2.5.0\e[39m (stable version)"
-echo -e "  \e[31mv2.3.5-dev\e[39m (development version - note: use 'v' prefix)"
+echo -e "  \e[31m2.5.5-dev\e[39m (development version - will auto-add 'v' prefix)"
+echo -e "  \e[31mv2.3.5-dev\e[39m (development version with 'v' prefix)"
 echo -e "  \e[31mv2.3.4\e[39m (stable version)"
 echo -e "  \e[31mb05d9cb5bb3c277b22a6070f04844e8a7951585b\e[39m (specific commit)"
 echo -e "  \e[31mb05d9cb\e[39m (short commit hash)"
 echo -e ""
-echo -e "\e[33mNote: The '2.5.5-dev' branch does not exist. Use 'v2.3.5-dev' instead.\e[39m"
+echo -e "\e[33mNote: Development versions will automatically get 'v' prefix if not provided.\e[39m"
 printf "%s" ""
 read -r Tmp_Input
 
diff --git a/tools/test_fixes.sh b/tools/test_fixes.sh
index 53d3a8c56..a0dadf009 100644
--- a/tools/test_fixes.sh
+++ b/tools/test_fixes.sh
@@ -10,11 +10,18 @@ echo ""
 echo "Test 1: Testing requirements file fallback logic..."
 echo "Testing non-existent branch (should show 404)..."
 if curl -s -I "https://raw.githubusercontent.com/usmannasir/cyberpanel/2.5.5-dev/requirments.txt" | grep -q "404 Not Found"; then
-    echo "✅ Non-existent branch correctly returns 404"
+    echo "✅ Non-existent branch (without 'v' prefix) correctly returns 404"
 else
     echo "❌ Non-existent branch test failed"
 fi
 
+echo "Testing v2.5.5-dev branch (should show 200)..."
+if curl -s -I "https://raw.githubusercontent.com/usmannasir/cyberpanel/v2.5.5-dev/requirments.txt" | grep -q "200 OK"; then
+    echo "✅ v2.5.5-dev branch correctly returns 200"
+else
+    echo "❌ v2.5.5-dev branch test failed"
+fi
+
 echo "Testing existing commit (should show 200)..."
 if curl -s -I "https://raw.githubusercontent.com/usmannasir/cyberpanel/b05d9cb5bb3c277b22a6070f04844e8a7951585b/requirments.txt" | grep -q "200 OK"; then
     echo "✅ Existing commit correctly returns 200"