diff --git a/.gitignore b/.gitignore
index 52ef87d58a7..6e4ca6e2c6f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -99,6 +99,9 @@ geoip/GeoIP.conf
 geoip/*.mmdb
 geoip/.geoipupdate.lock
 
+# hard stop version tracking
+.sentry-hard-stop
+
 # integration testing
 _integration-test/custom-ca-roots/nginx/*
 sentry/test-custom-ca-roots.py
diff --git a/hard-stop.json b/hard-stop.json
new file mode 100644
index 00000000000..d05ef7ee837
--- /dev/null
+++ b/hard-stop.json
@@ -0,0 +1,13 @@
+{
+    "hard_stops": [
+        "9.1.2",
+        "21.5.0",
+        "21.6.3",
+        "23.6.2",
+        "23.11.0",
+        "24.8.0",
+        "25.5.1",
+        "26.5.0",
+        "26.7.0"
+    ]
+}
diff --git a/install.sh b/install.sh
index 3b4d9b50011..2cdef4c7f23 100755
--- a/install.sh
+++ b/install.sh
@@ -21,6 +21,7 @@ source install/dc-detect-version.sh
 source install/error-handling.sh
 # We set the trap at the top level so that we get better tracebacks.
 trap_with_arg cleanup ERR INT TERM EXIT
+source install/check-hard-stop.sh
 source install/check-latest-commit.sh
 source install/check-minimum-requirements.sh
 
diff --git a/install/check-hard-stop.sh b/install/check-hard-stop.sh
new file mode 100644
index 00000000000..f1879621037
--- /dev/null
+++ b/install/check-hard-stop.sh
@@ -0,0 +1,206 @@
+# The idea of this file is to prevent users from skipping a hard stop.
+# This is done by creating a file in /var/run/sentry-hard-stop (or anything set
+# in HARD_STOP_FILE) and checking for its existence before. If the file exists,
+# we assume (and trust) that it's the latest version of the self-hosted sentry
+# version, and no further check (git tag, values on `.env` ) would be done.
+# Otherwise, we assume either this is the first installation, or the first
+# time after this file is being written, and write into that file (by reading
+# either the Git tag or values on `.env` or `.env.custom`).
+#
+# If the "reading" part fails anyway, we would skip this process and continue
+# with the installation.
+#
+# If the user skipped a hard stop, we would halt the installation (or maybe,
+# cancel it altogether), and ask for confirmation.
+#
+# This bit is written by a human.
+
+echo "${_group}Checking for hard stop ... "
+
+latest_version_file=${HARD_STOP_FILE:-".sentry-hard-stop"}
+# This should be a bash array string, and should be equivalent with the list
+# on https://develop.sentry.dev/self-hosted/releases/#hard-stops
+mapfile -t hard_stops < <(cat hard-stop.json | $jq -r '.hard_stops[]')
+
+_write_latest_version() {
+  echo "$1" >"$latest_version_file"
+}
+
+# Helper function to parse version components
+# BASH_REMATCH requires Bash 3.0+
+_parse_version_components() {
+  local ver="$1"
+  if [[ $ver =~ ^(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(-[0-9A-Za-z.-]*)?(\+[0-9A-Za-z.-]*)?$ ]]; then
+    echo "${BASH_REMATCH[1]} ${BASH_REMATCH[2]} ${BASH_REMATCH[3]} ${BASH_REMATCH[4]#-} ${BASH_REMATCH[5]#+}"
+  else
+    echo ""
+  fi
+}
+
+# Compare two calver versions
+# Usage: compare_calver "1.2.3" "1.2.4"
+# Returns: -1 if first < second, 0 if equal, 1 if first > second
+#
+# This bit is written by Claude Haiku 4.5.
+compare_calver() {
+  local v1="$1"
+  local v2="$2"
+
+  if [[ -z "$v1" ]] || [[ -z "$v2" ]]; then
+    echo -e "ERROR: Invalid CalVer format" >&2
+    return 2
+  fi
+
+  # Remove leading 'v' if present
+  v1="${v1#v}"
+  v2="${v2#v}"
+
+  # Extract components
+  local parsed1=$(_parse_version_components "$v1")
+  local parsed2=$(_parse_version_components "$v2")
+
+  if [[ -z "$parsed1" ]] || [[ -z "$parsed2" ]]; then
+    echo -e "ERROR: Invalid CalVer format" >&2
+    return 2
+  fi
+
+  # Compare major.minor.patch
+  local arr1=($parsed1)
+  local arr2=($parsed2)
+
+  if ((arr1[0] > arr2[0])); then
+    return 1
+  elif ((arr1[0] < arr2[0])); then
+    return -1
+  fi
+
+  if ((arr1[1] > arr2[1])); then
+    return 1
+  elif ((arr1[1] < arr2[1])); then
+    return -1
+  fi
+
+  if ((arr1[2] > arr2[2])); then
+    return 1
+  elif ((arr1[2] < arr2[2])); then
+    return -1
+  fi
+
+  return 0 # Equal
+}
+
+# Acquire the new version. This is done by reading `.env` / `.env.custom`
+# for Docker image tags; or by reading the Git tag for the current commit
+declare new_version=""
+# if `.env.custom` exists, prioritize it over `.env`
+if [[ -f ".env.custom" ]]; then
+  new_version=$(grep -E '^SENTRY_IMAGE=' .env.custom | sed 's/^.*=//' | cut -d: -f2 || true)
+fi
+
+if [[ -z "$new_version" ]]; then
+  new_version=$(grep -E '^SENTRY_IMAGE=' .env | sed 's/^.*=//' | cut -d: -f2 || true)
+fi
+
+if [[ -z "$new_version" ]]; then
+  # Check whether `git` exists as a command, and `.git` directory exists
+  if [[ -n "$(command -v git)" ]] && [[ -d "../.git" || -d "./.git" ]]; then
+    # Get the latest tag from the repository
+    new_version=$(git describe --tags --abbrev=0)
+  fi
+fi
+
+# If the `new_version` is still empty, we emit a warning that
+# they're on their own
+if [[ -z "$new_version" ]]; then
+  echo "--------------------------------------------------------------------------------"
+  echo "WARNING: Could not determine the current version of the self-hosted Sentry"
+  echo "to perform a hard stop check. Assuming you know what you're doing. Good luck."
+  echo "--------------------------------------------------------------------------------"
+fi
+
+# If the `new_version` is empty, we cannot perform any hard stop check.
+# This means the version detection failed across all methods. We already
+# warned the user above, so we skip the check and continue with the installation.
+if [[ -z "$new_version" ]]; then
+  echo "Skipping hard stop check: unable to determine the current version."
+elif [[ "$new_version" == "nightly" ]]; then
+  # If the `new_version` is nightly, we emit a different warning.
+  # This is for fun.
+  echo "--------------------------------------------------------------------------------"
+  echo "WARNING: Hello, dear brave traveler. You are installing the nightly version."
+  echo "The hard stop check is skipped for this version. We wish you a safe journey."
+  echo "Good luck."
+  echo "--------------------------------------------------------------------------------"
+else
+  # Only perform the hard stop check when we have a parseable semver version.
+  # Skip for empty or non-semver versions (e.g. "nightly") — the warnings above
+  # already informed the user.
+
+  # Acquire the current version. Read the file.
+  declare current_version=""
+  if [[ -f "$latest_version_file" ]]; then
+    current_version=$(cat "$latest_version_file")
+  fi
+
+  # We perform some checks if the `current_version` is not empty.
+  if [[ -n "$current_version" ]]; then
+    # We iterate over the list of hard stops, and check whether the current
+    # version is below any of them.
+    local _wrote_version=0
+    for hard_stop in "${hard_stops[@]}"; do
+      compare_result=$(compare_calver "$current_version" "$hard_stop")
+      if [[ "$compare_result" == 0 ]]; then
+        # equal, this is correct, they're visiting a hard stop
+        _write_latest_version "$new_version"
+        _wrote_version=1
+        break
+      elif [[ "$compare_result" == 1 ]]; then
+        # the current version is greater than the current hard stop loop, we continue
+        continue
+      elif [[ "$compare_result" == -1 ]]; then
+        # the current version is less than the current hard stop loop
+        # we alert the user and provide a confirmation
+        echo "--------------------------------------------------------------------------------"
+        echo
+        echo "WARNING: Your new version ($new_version) will skip a required hard stop of $hard_stop."
+        echo "It is recommended to stop the current installation, and go through the hard stop first."
+        echo "Otherwise, you may encounter unexpected behaviors, such as migration failures, or data loss."
+        echo
+        echo "For future reference, please visit https://develop.sentry.dev/self-hosted/releases/#hard-stops"
+        echo
+        echo "Do you wish to continue? [y/N]"
+        read -r confirmation
+
+        if [[ "$confirmation" == "y" ]]; then
+          _write_latest_version "$new_version"
+          _wrote_version=1
+          break
+        else
+          echo "Canceled. 😅"
+          exit 1
+        fi
+      elif [[ "$compare_result" == 2 ]]; then
+        # invalid version, we exit
+        echo "ERROR: Invalid version in $latest_version_file"
+        exit 1
+      else
+        # a bug on our end, the `compare_result` returns unexpected value
+        echo 'ERROR: Unexpected return value from `compare_calver` function. This is a bug on our end.'
+        echo "The 'compare_result' value is: $compare_result"
+        exit 2
+      fi
+    done
+    # If the loop completed without writing (current_version > all hard stops),
+    # update the tracking file so the version stays current.
+    if [[ "$_wrote_version" -eq 0 ]]; then
+      _write_latest_version "$new_version"
+    fi
+  else
+    # If the `current_version` is empty (or the file does not exists), we assume
+    # this is a new installation.
+    echo "Self-hosted Sentry version tracking file not found. No hard stop check is needed."
+    _write_latest_version "$new_version"
+  fi
+fi
+
+echo "${_endgroup}"