1 files changed, 5 insertions, 0 deletions
diff --git a/UPGRADING b/UPGRADING
index 2607cc2918..adc813349d 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -329,6 +329,11 @@ JSON:
   . Support for ODBCRouter has been removed.
   . Support for Birdstep has been removed.
 
+PCRE:
+  . The PCRE extension has been upgraded to PCRE2, which may cause minor
+    behavioral changes, and augments the existing regular expression syntax.
+    See <https://wiki.php.net/rfc/pcre2-migration> for details.
+
  ZIP:
   . Bundled libzip has been dropped,
     system library is now required.