From b599fdb197c6b80d3be334899b9e9620492656b9 Mon Sep 17 00:00:00 2001
From: Max Ryabinin <mryabinin0@gmail.com>
Date: Wed, 14 Jun 2023 19:27:13 +0200
Subject: [PATCH] Only rearrange weight if it exists

---
 bitsandbytes/nn/modules.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/bitsandbytes/nn/modules.py b/bitsandbytes/nn/modules.py
index b806e94..b10d45a 100644
--- a/bitsandbytes/nn/modules.py
+++ b/bitsandbytes/nn/modules.py
@@ -307,7 +307,10 @@ class Int8Params(torch.nn.Parameter):
 
 
 def maybe_rearrange_weight(state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs):
-    weight = state_dict[f"{prefix}weight"]
+    weight = state_dict.get(f"{prefix}weight")
+    if weight is None:
+        # if the state dict has no weights for this layer (e.g., LoRA finetuning), do nothing
+        return
     weight_format = state_dict.pop(f"{prefix}weight_format", "row")
 
     if weight_format != "row":