Backport https://github.com/flyinghead/flycast/commit/190ab6690ac6bcb5218fba55d7c50fc7954ab65c

core/rend/vulkan/texture.cpp

@@ -254,7 +254,13 @@ void Texture::SetImage(u32 srcSize, void *srcData, bool isNew, bool genMipmaps)
 
 	void* data;
 	if (needsStaging)
+   {
+      if (!stagingBufferData)
+         // This can happen if a texture is first created for RTT, then later updated
+         stagingBufferData = std::unique_ptr<BufferData>(new BufferData(srcSize, vk::BufferUsageFlagBits::eTransferSrc));
+
 		data = stagingBufferData->MapMemory();
+   }
 	else
 		data = allocation.MapMemory();
 	verify(data != nullptr);