diff --git a/README.md b/README.md
index b5cb505c..73c7ea5b 100644
--- a/README.md
+++ b/README.md
@@ -174,20 +174,10 @@ go build -o cyberstrike-ai cmd/server/main.go
 
 ### Version Update (No Breaking Changes)
 
-**CyberStrikeAI one-click upgrade (recommended):**
-1. (First time) enable the script: `chmod +x upgrade.sh`
-2. Upgrade with: `./upgrade.sh` (optional flags: `--tag vX.Y.Z`, `--no-venv`, `--preserve-custom`, `--yes`)
-3. The script will back up your `config.yaml` and `data/`, upgrade the code from GitHub Release, update `config.yaml`'s `version`, then restart the server.
-
-Recommended one-liner:
-`chmod +x upgrade.sh && ./upgrade.sh --yes`
-
-If something goes wrong, you can restore from `.upgrade-backup/` (or manually copy `/data` and `config.yaml` back) and run `./run.sh` again.
-
-Requirements / tips:
-* You need `curl` or `wget` for downloading Release packages.
-* `rsync` is recommended/required for the safe code sync.
-* If GitHub API rate-limits you, set `export GITHUB_TOKEN="..."` before running `./upgrade.sh`.
+**CyberStrikeAI version update (when there are no compatibility changes):**
+1. Download the latest source code.
+2. Copy the old project's `/data` folder and `config.yaml` file into the new source directory.
+3. Restart with: `chmod +x run.sh && ./run.sh`
 
 ⚠️ **Note:** This procedure only applies to version updates without compatibility or breaking changes. If a release includes compatibility changes, this method may not apply.
 
diff --git a/README_CN.md b/README_CN.md
index 5f75fff7..2d45b58c 100644
--- a/README_CN.md
+++ b/README_CN.md
@@ -173,19 +173,9 @@ go build -o cyberstrike-ai cmd/server/main.go
 
 ### CyberStrikeAI 版本更新（无兼容性问题）
 
-1. （首次使用）启用脚本：`chmod +x upgrade.sh`
-2. 一键升级：`./upgrade.sh`（可选参数：`--tag vX.Y.Z`、`--no-venv`、`--preserve-custom`、`--yes`）
-3. 脚本会备份你的 `config.yaml` 和 `data/`，从 GitHub Release 升级代码，更新 `config.yaml` 的 `version` 字段后重启服务。
-
-推荐的一键指令：
-`chmod +x upgrade.sh && ./upgrade.sh --yes`
-
-如果升级失败，可以从 `.upgrade-backup/` 恢复，或按旧方式手动拷贝 `/data` 和 `config.yaml` 后再运行 `./run.sh`。
-
-依赖/提示：
-* 需要 `curl` 或 `wget` 用于下载 GitHub Release 包。
-* 建议/需要 `rsync` 用于安全同步代码。
-* 如果遇到 GitHub API 限流，运行前设置 `export GITHUB_TOKEN="..."` 再执行 `./upgrade.sh`。
+1. 下载最新源代码；
+2. 将旧项目的 `/data` 文件夹、`config.yaml` 文件复制至新版源代码目录；
+3. 执行命令重启：`chmod +x run.sh && ./run.sh`
 
 ⚠️ **注意：** 仅适用于无兼容性变更的版本更新。若版本存在兼容性调整，此方法不适用。
 
diff --git a/upgrade.sh b/upgrade.sh
index d6a6bce7..3b7ec110 100644
--- a/upgrade.sh
+++ b/upgrade.sh
@@ -69,9 +69,11 @@ http_get() {
   if have_cmd curl; then
     # If GITHUB_TOKEN is provided, use it for api.github.com to avoid low rate limits.
     if [[ -n "${GITHUB_TOKEN:-}" && "$1" == https://api.github.com/* ]]; then
-      curl -fsSL -H "Authorization: Bearer ${GITHUB_TOKEN}" "$1"
+      # Do not use `-f` so we can parse GitHub error JSON bodies and show `message`.
+      curl -sSL -H "Authorization: Bearer ${GITHUB_TOKEN}" "$1"
     else
-      curl -fsSL "$1"
+      # Do not use `-f` so we can parse GitHub error JSON bodies and show `message`.
+      curl -sSL "$1"
     fi
   elif have_cmd wget; then
     wget -qO- "$1"
@@ -208,11 +210,33 @@ PY
   if [[ -z "$TAG" ]]; then
     local msg
     msg="$(printf '%s' "$json" | python3 -c "import sys,json; d=json.loads(sys.stdin.read() or '{}'); print(d.get('message',''))" 2>/dev/null || true)"
+
+    # Fallback: try query releases list (sometimes latest endpoint returns error JSON without tag_name).
+    local fallback_url="https://api.github.com/repos/${GITHUB_REPO}/releases?per_page=1"
+    info "Fallback to: ${fallback_url}"
+    local fallback_json
+    fallback_json="$(http_get "$fallback_url" 2>/dev/null || true)"
+    local fallback_tag
+    fallback_tag="$(printf '%s' "$fallback_json" | python3 -c "import sys,json; d=json.loads(sys.stdin.read() or '[]'); print(d[0].get('tag_name','') if isinstance(d,list) and d else '')" 2>/dev/null || true)"
+
+    if [[ -n "$fallback_tag" ]]; then
+      TAG="$fallback_tag"
+      info "Latest Release tag (fallback): $TAG"
+      return 0
+    fi
+
+    local snippet
+    snippet="$(printf '%s' "$json" | python3 -c "import sys; s=sys.stdin.read(); print(s[:300].replace('\\n',' '))" 2>/dev/null || true)"
+
     if [[ -n "$msg" ]]; then
       err "Failed to fetch latest tag: ${msg}"
     else
-      err "Failed to fetch latest tag. Please try using --tag to specify the version."
+      err "Failed to fetch latest tag."
     fi
+    if [[ -n "$snippet" ]]; then
+      err "API response snippet: ${snippet}"
+    fi
+    err "Please try using --tag to specify the version, or set export GITHUB_TOKEN=\"...\"."
     exit 1
   fi
   info "Latest Release tag: $TAG"