diff --git a/src/bits.h b/src/bits.h
index fc7b939e..3d3e3921 100644
--- a/src/bits.h
+++ b/src/bits.h
@@ -476,8 +476,10 @@ typedef struct MDBX_lockinfo {
    (uint16_t)(MDBX_LOCKINFO_WHOLE_SIZE + MDBX_CACHELINE_SIZE - 1))
 
 #define MDBX_DATA_MAGIC ((MDBX_MAGIC << 8) + MDBX_DATA_VERSION)
+#define MDBX_DATA_MAGIC_DEVEL ((MDBX_MAGIC << 8) + 255)
 
 #define MDBX_LOCK_MAGIC ((MDBX_MAGIC << 8) + MDBX_LOCK_VERSION)
+#define MDBX_LOCK_MAGIC_DEVEL ((MDBX_MAGIC << 8) + 255)
 
 #ifndef MDBX_ASSUME_MALLOC_OVERHEAD
 #define MDBX_ASSUME_MALLOC_OVERHEAD (sizeof(void *) * 2u)
diff --git a/src/mdbx.c b/src/mdbx.c
index e4f344ae..75505966 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -4928,7 +4928,8 @@ static int __cold mdbx_read_header(MDBX_env *env, MDBX_meta *meta,
       mdbx_info("meta[%u] was updated, re-read it", meta_number);
     }
 
-    if (page.mp_meta.mm_magic_and_version != MDBX_DATA_MAGIC) {
+    if (page.mp_meta.mm_magic_and_version != MDBX_DATA_MAGIC &&
+        page.mp_meta.mm_magic_and_version != MDBX_DATA_MAGIC_DEVEL) {
       mdbx_error("meta[%u] has invalid magic/version %" PRIx64, meta_number,
                  page.mp_meta.mm_magic_and_version);
       return ((page.mp_meta.mm_magic_and_version >> 8) != MDBX_MAGIC)
@@ -6298,7 +6299,8 @@ static int __cold mdbx_setup_lck(MDBX_env *env, char *lck_pathname,
     env->me_lck->mti_magic_and_version = MDBX_LOCK_MAGIC;
     env->me_lck->mti_os_and_format = MDBX_LOCK_FORMAT;
   } else {
-    if (env->me_lck->mti_magic_and_version != MDBX_LOCK_MAGIC) {
+    if (env->me_lck->mti_magic_and_version != MDBX_LOCK_MAGIC &&
+        env->me_lck->mti_magic_and_version != MDBX_LOCK_MAGIC_DEVEL) {
       mdbx_error("lock region has invalid magic/version");
       return ((env->me_lck->mti_magic_and_version >> 8) != MDBX_MAGIC)
                  ? MDBX_INVALID