diff --git a/pyocd/target/family/target_nRF54L.py b/pyocd/target/family/target_nRF54L.py
index b81968572..c94ee0c4d 100644
--- a/pyocd/target/family/target_nRF54L.py
+++ b/pyocd/target/family/target_nRF54L.py
@@ -143,7 +143,13 @@ def check_flash_security(self):
             if self.session.options.get('auto_unlock'):
                 LOG.warning("%s APPROTECT enabled: will try to unlock via mass erase", self.part_number)
 
-                self.mass_erase()
+                if not self.mass_erase():
+                    LOG.error("%s: mass erase failed", self.part_number)
+                    raise exceptions.TargetError("unable to unlock device")
+                # Cached badness from create_ap run during AP lockout prevents memory accesses
+                # through the AHB-AP from succeeding.
+                self._discoverer._create_1_ap(AHB_AP_NUM)
+                self.fixup_rom_base()
         else:
             LOG.warning("%s is not in a secure state", self.part_number)