diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index 0236886..84de986 100644
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -2711,6 +2711,18 @@
         return false;
     }
 
+    /* The epoch data format is defined for AEAD ciphers only. A peer may push
+     * the tag along with a non-AEAD cipher, so this has to be checked here
+     * rather than trusted */
+    if (epoch_data && !cipher_kt_mode_aead(c->options.ciphername))
+    {
+        msg(D_PUSH_ERRORS,
+            "OPTIONS ERROR: Epoch key data format tag requires an AEAD "
+            "cipher, but '%s' was negotiated.",
+            c->options.ciphername);
+        return false;
+    }
+
 
     if (found & OPT_P_PUSH_MTU)
     {
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index b5ab51e..2c7e672 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -1413,10 +1413,14 @@
     {
         if (!cipher_kt_mode_aead(key_type->cipher))
         {
-            msg(M_FATAL,
-                "AEAD cipher (currently %s) "
+            /* The pulled options are validated in do_deferred_options(), so
+             * reaching this point means a code path escaped that check. Fail
+             * the session instead of the whole process */
+            msg(D_TLS_ERRORS,
+                "TLS Error: AEAD cipher (currently %s) "
                 "required for epoch data format.",
                 cipher_kt_name(key_type->cipher));
+            return KEY_GEN_FAILED;
         }
         init_epoch_keys(ks, multi, key_type, server, key2);
     }