diff --git a/.github/workflows/publish-release.yml b/.github/workflows/publish-release.yml
index 91642f81..77bdb5db 100644
--- a/.github/workflows/publish-release.yml
+++ b/.github/workflows/publish-release.yml
@@ -60,6 +60,12 @@ jobs:
           INTERVAL=30
           ELAPSED=0
 
+          # RC tags: publish with whatever assets are available (minimum: Linux >= 4 OR macOS >= 4)
+          # Stable tags: require all platforms (Linux >= 8, macOS >= 4, Windows >= 8)
+          # jane: RC releases exist for downstream testing — a partial release
+          # (e.g. Windows fails with 504) is still useful for testing Linux/macOS.
+          IS_RC=$(echo "$TAG" | grep -qiE '(rc|beta|alpha|dev)\.' && echo "true" || echo "false")
+
           while [ $ELAPSED -lt $MAX_WAIT ]; do
             ASSETS_JSON=$(gh release view "$TAG" --repo "${{ github.repository }}" --json assets 2>/dev/null || echo '{"assets":[]}')
 
@@ -67,11 +73,20 @@ jobs:
             MACOS=$(echo "$ASSETS_JSON" | jq '[.assets[].name | select(endswith(".tar.gz") and contains("macos"))] | length' 2>/dev/null || echo 0)
             WIN=$(echo "$ASSETS_JSON" | jq '[.assets[].name | select(endswith(".zip") and contains("x86_64"))] | length' 2>/dev/null || echo 0)
 
-            echo "Assets: Linux=$LINUX, macOS=$MACOS, Windows=$WIN (${ELAPSED}s / ${MAX_WAIT}s)"
+            echo "Assets: Linux=$LINUX, macOS=$MACOS, Windows=$WIN (${ELAPSED}s / ${MAX_WAIT}s) RC=$IS_RC"
 
-            if [ "$LINUX" -ge 8 ] && [ "$MACOS" -ge 4 ] && [ "$WIN" -ge 8 ]; then
-              echo "All platform assets present"
-              exit 0
+            if [ "$IS_RC" = "true" ]; then
+              # RC: sufficient if Linux OR macOS assets are present
+              if [ "$LINUX" -ge 4 ] || [ "$MACOS" -ge 4 ]; then
+                echo "RC: sufficient assets for pre-release (Linux=$LINUX, macOS=$MACOS, Windows=$WIN)"
+                exit 0
+              fi
+            else
+              # Stable: require all platforms
+              if [ "$LINUX" -ge 8 ] && [ "$MACOS" -ge 4 ] && [ "$WIN" -ge 8 ]; then
+                echo "All platform assets present"
+                exit 0
+              fi
             fi
 
             sleep $INTERVAL
@@ -96,6 +111,14 @@ jobs:
 
           echo "Asset counts: Linux=${LINUX_COUNT}, macOS=${MACOS_COUNT}, Windows=${WINDOWS_COUNT}, Total=${TOTAL_COUNT}"
 
+          # RC tags: skip strict validation (partial releases are OK for testing)
+          if echo "$TAG" | grep -qiE '(rc|beta|alpha|dev)\.'; then
+            echo "RC tag detected — skipping strict asset validation"
+            [ "$TOTAL_COUNT" -ge 4 ] || { echo "ERROR: RC needs at least 4 assets, got $TOTAL_COUNT"; exit 1; }
+            echo "RC: $TOTAL_COUNT assets (sufficient for pre-release)"
+            exit 0
+          fi
+
           fail=0
           [ "$LINUX_COUNT" -lt 8 ] && { echo "ERROR: Linux has only $LINUX_COUNT bundles (expected >= 8)"; fail=1; }
           [ "$MACOS_COUNT" -lt 4 ] && { echo "ERROR: macOS has only $MACOS_COUNT bundles (expected >= 4)"; fail=1; }
diff --git a/.github/workflows/release-linux.yml b/.github/workflows/release-linux.yml
index 2f6f8713..6ccf6b48 100644
--- a/.github/workflows/release-linux.yml
+++ b/.github/workflows/release-linux.yml
@@ -188,6 +188,7 @@ jobs:
           fi
       
       - name: Install Firebird SDK
+        if: steps.cache-fb-sdk.outputs.cache-hit != 'true'
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
@@ -294,7 +295,21 @@ jobs:
         uses: ./.github/actions/determine-php-version
         with:
           php-minor: ${{ matrix.php }}
-      
+
+      - name: Cache PHP source
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5
+        id: cache-php-src
+        with:
+          path: /tmp/php-src-cached
+          key: php-src-${{ steps.php-version.outputs.full_version }}
+
+      - name: Cache Firebird SDK
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5
+        id: cache-fb-sdk
+        with:
+          path: /opt/firebird
+          key: firebird-sdk-${{ env.FB_VERSION }}-${{ env.FB_BUILD }}-${{ matrix.fb_arch }}
+
       - name: Install PHP ${{ matrix.php }} (${{ matrix.variant }})
         shell: bash
         run: |
@@ -304,14 +319,36 @@ jobs:
           
           echo "Building PHP ${FULL_VERSION} (${VARIANT})..."
           
-          # Download PHP source
-          curl -fsSL "https://www.php.net/distributions/php-${FULL_VERSION}.tar.xz" \
-            -o /tmp/php.tar.xz
-          
-          mkdir -p /tmp/php-src
-          tar -xJf /tmp/php.tar.xz -C /tmp/php-src --strip-components=1
+          # Use cached PHP source if available (avoids 504 from php.net)
+          if [ -d /tmp/php-src-cached/php-src ]; then
+            echo "Using cached PHP source"
+            cp -a /tmp/php-src-cached/php-src /tmp/php-src
+          else
+            # Download PHP source with retry (php.net sometimes returns 504)
+            DELAY=10
+            for attempt in 1 2 3 4 5; do
+              echo "Downloading PHP source (attempt ${attempt}/5)..."
+              if curl -fsSL --retry 3 --retry-delay 5 \
+                  "https://www.php.net/distributions/php-${FULL_VERSION}.tar.xz" \
+                  -o /tmp/php.tar.xz; then
+                FSIZE=$(stat -c%s /tmp/php.tar.xz 2>/dev/null || echo "0")
+                if [ "${FSIZE}" -gt 5000000 ]; then
+                  echo "Download succeeded (${FSIZE} bytes)"
+                  break
+                fi
+                echo "File too small (${FSIZE} bytes), discarding"
+                rm -f /tmp/php.tar.xz
+              fi
+              [ "${attempt}" -lt 5 ] && echo "Sleeping ${DELAY}s..." && sleep "${DELAY}" && DELAY=$((DELAY * 2))
+            done
+            [ -f /tmp/php.tar.xz ] || { echo "ERROR: PHP source download failed after 5 attempts" >&2; exit 1; }
+            
+            mkdir -p /tmp/php-src /tmp/php-src-cached
+            tar -xJf /tmp/php.tar.xz -C /tmp/php-src --strip-components=1
+            cp -a /tmp/php-src /tmp/php-src-cached/
+          fi
           cd /tmp/php-src
-          
+
           # Configure options
           CONFIGURE_OPTS=(
             "--prefix=${INSTALL_DIR}"
diff --git a/.github/workflows/release-windows.yml b/.github/workflows/release-windows.yml
index 0a88b8bb..1b64246c 100644
--- a/.github/workflows/release-windows.yml
+++ b/.github/workflows/release-windows.yml
@@ -100,6 +100,27 @@ jobs:
           echo "FIREBIRD_HOME=$sdkPath" >> $env:GITHUB_ENV
           echo "$sdkPath\bin" >> $env:GITHUB_PATH
 
+      - name: Check PHP SDK availability
+        shell: pwsh
+        run: |
+          # Check if downloads.php.net is reachable before attempting the build.
+          # jane: php-windows-builder downloads PHP SDK deps from downloads.php.net
+          # which intermittently returns 504 Gateway Timeout. This check gives early
+          # visibility and a retry window before the build step fails.
+          $vs = if ('${{ matrix.php-version }}' -ge '8.4') { 'vs17' } else { 'vs16' }
+          $url = "https://downloads.php.net/~windows/php-sdk/deps/$vs/x64/"
+          for ($i = 1; $i -le 5; $i++) {
+            try {
+              $resp = Invoke-WebRequest -Uri $url -Method Head -TimeoutSec 10
+              Write-Host "PHP SDK available (HTTP $($resp.StatusCode))"
+              exit 0
+            } catch {
+              Write-Host "Attempt $i/5: PHP SDK not available ($($_.Exception.Message))"
+              if ($i -lt 5) { Start-Sleep -Seconds 30 }
+            }
+          }
+          Write-Host "::warning::PHP SDK deps unavailable, build may fail with 504"
+
       - name: Resolve release tag
         id: reltag
         shell: bash
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9848697e..06f36dd0 100755
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,37 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [13.0.1-rc.1] - 2026-07-21
+
+### CI/CD Pipeline Fixes
+
+- **build-extension action**: `phpize-clean` default changed from `false` to `true`
+  + stale `.so` removal before `phpize --clean` to prevent header/library version
+  mismatches when the source tree is shared between Docker containers with different
+  Firebird client versions (#558)
+- **ci.yml**: Added stale `.so` removal + `phpize --clean` to `pdo_fbird` standalone
+  build step
+- **.deb packaging**: Fixed Docker image naming for Ubuntu distros — `php:*-cli-jammy`
+  and `php:*-cli-noble` don't exist on Docker Hub. Now uses `ubuntu:22.04`/`ubuntu:24.04`
+  base images + Sury PPA for PHP installation
+- **release-linux.yml**: Added PHP source caching + Firebird SDK caching + retry logic
+  (5 attempts with exponential backoff) for `php.net` 504 errors
+- **release-windows.yml**: Added PHP SDK availability check before build (early
+  visibility + retry for `downloads.php.net` 504 errors)
+- **publish-release.yml**: Relaxed asset requirements for RC tags — publishes as
+  pre-release if Linux >= 4 OR macOS >= 4 assets are present (instead of requiring
+  all platforms). Stable releases still require all platforms.
+- **.gitignore**: Added `/debian/` and `/dist/` build output directories
+
+### SIGSEGV Fix (PHP 8.5/FB3)
+
+- **Root cause**: Stale `.so` compiled against FB 5.0 headers (`FB_API_VER=50`),
+  loaded with FB 3.0 client library. `IResultSet::close()` dispatched through a
+  vtable slot (`deprecatedClose`) that doesn't exist in FB 3.0's `libfbclient`
+  → NULL function pointer → SIGSEGV during shutdown.
+- **Fix**: `phpize --clean` + `rm -f stale .so` before every build (PR #558)
+- **Validation**: 12/12 containers pass (4,321 tests, 0 failures)
+
 ## [13.0.1] - 2026-07-20
 
 ### v13.0.1 — Post-Release Bugfixes
diff --git a/VERSION.txt b/VERSION.txt
index 5cb7d856..452d34d4 100644
--- a/VERSION.txt
+++ b/VERSION.txt
@@ -1 +1 @@
-13.0.1
+13.0.1-rc.1
diff --git a/packaging/debian/build-matrix.sh b/packaging/debian/build-matrix.sh
index c9e29a5a..a8d2bc3a 100755
--- a/packaging/debian/build-matrix.sh
+++ b/packaging/debian/build-matrix.sh
@@ -117,14 +117,28 @@ get_docker_image() {
     esac
 
     case "$distro" in
+        # Debian: official PHP Docker images exist with Debian codenames
         bookworm) echo "php:${php_ver}-cli-bookworm" ;;
         trixie)   echo "php:${php_ver}-cli-trixie" ;;
-        jammy)    echo "php:${php_ver}-cli-jammy" ;;
-        noble)    echo "php:${php_ver}-cli-noble" ;;
+        # Ubuntu: no official PHP Docker images (only Debian codenames exist).
+        # Use Ubuntu base image + install PHP from packages.sury.org PPA.
+        # jane: PHP Docker images only use Debian codenames (bookworm, trixie),
+        # never Ubuntu codenames (jammy, noble). The Sury PPA provides PHP for
+        # both Debian AND Ubuntu suites.
+        jammy)    echo "ubuntu:22.04" ;;
+        noble)    echo "ubuntu:24.04" ;;
         *) echo ""; return 1 ;;
     esac
 }
 
+# Check if a distro is Ubuntu (needs Sury PPA for PHP)
+is_ubuntu() {
+    case "$1" in
+        jammy|noble) echo "true" ;;
+        *) echo "false" ;;
+    esac
+}
+
 # Map arch name to Docker platform
 get_docker_platform() {
     local arch="$1"
@@ -205,11 +219,25 @@ build_package() {
         -e FB_ROOT="${fb_mount}" \
         "$docker_image" \
         bash -c "export DEBIAN_FRONTEND=noninteractive && \
-                 apt-get update -qq && \
-                 apt-get install -y -qq --no-install-recommends \
-                     autoconf build-essential gcc g++ make libtool bison re2c \
-                     libicu-dev libxml2-dev libtommath1 patchelf dpkg-dev debhelper \
-                     jq curl wget git ca-certificates && \
+                 $(if [ "$(is_ubuntu "$distro")" = "true" ]; then
+                     echo "apt-get update -qq && \
+                     apt-get install -y -qq lsb-release ca-certificates curl && \
+                     curl -sSLo /tmp/keyring.deb https://packages.sury.org/debsuryorg-archive-keyring.deb && \
+                     dpkg -i /tmp/keyring.deb && \
+                     printf 'Types: deb\nURIs: https://packages.sury.org/php/\nSuites: \$(lsb_release -sc)\nComponents: main\nSigned-By: /usr/share/keyrings/debsuryorg-archive-keyring.gpg\n' > /etc/apt/sources.list.d/php.sources && \
+                     apt-get update -qq && \
+                     apt-get install -y -qq --no-install-recommends \
+                         php${php_ver}-cli php${php_ver}-dev \
+                         autoconf build-essential gcc g++ make libtool bison re2c \
+                         libicu-dev libxml2-dev libtommath1 patchelf dpkg-dev debhelper \
+                         jq curl wget git ca-certificates &&"
+                 else
+                     echo "apt-get update -qq && \
+                     apt-get install -y -qq --no-install-recommends \
+                         autoconf build-essential gcc g++ make libtool bison re2c \
+                         libicu-dev libxml2-dev libtommath1 patchelf dpkg-dev debhelper \
+                         jq curl wget git ca-certificates &&"
+                 fi) \
                  cd /ext && bash packaging/debian/build.sh --php-version $php_ver --distro $distro --arch $arch --output-dir /output" \
         > "$result_log" 2>&1 || exit_code=$?
 
diff --git a/stubs/firebird-classes.php b/stubs/firebird-classes.php
index 8a366069..ca96729d 100644
--- a/stubs/firebird-classes.php
+++ b/stubs/firebird-classes.php
@@ -7,7 +7,7 @@
  * C extension. These are used by static analysis tools and IDEs.
  *
  * @package   php-firebird-stubs
- * @version   13.0.1
+ * @version   13.0.1-rc.1
  * @author    satware AG <info@satware.com>
  * @copyright 2025 satware AG
  * @license   PHP-3.01 https://www.php.net/license/3_01.txt
diff --git a/stubs/firebird-stubs.php b/stubs/firebird-stubs.php
index 3fc674fe..4d7fcf43 100644
--- a/stubs/firebird-stubs.php
+++ b/stubs/firebird-stubs.php
@@ -10,7 +10,7 @@
  * This stub file does not contain any implementation.
  *
  * @package   php-firebird-stubs
- * @version   13.0.1
+ * @version   13.0.1-rc.1
  * @author    satware AG <info@satware.com>
  * @copyright 2025-2026 satware AG
  * @license   PHP-3.01 https://www.php.net/license/3_01.txt
diff --git a/stubs/pdo-fbird-stubs.php b/stubs/pdo-fbird-stubs.php
index 20c395ad..646e0eea 100644
--- a/stubs/pdo-fbird-stubs.php
+++ b/stubs/pdo-fbird-stubs.php
@@ -15,7 +15,7 @@
  *                  'SYSDBA', 'masterkey');
  *
  * @package   php-firebird-stubs
- * @version   13.0.1
+ * @version   13.0.1-rc.1
  * @author    satware AG <info@satware.com>
  * @copyright 2025-2026 satware AG
  * @license   PHP-3.01 https://www.php.net/license/3_01.txt