Can't upload txt/pdf file with golang lib

[l111]

I am trying to use snippet code from this doc gemini golang doc under " Locally stored PDFs" section.

My code:

func UploadPDFGemini() {

	ctx := context.Background()
	client, _ := genai.NewClient(ctx, &genai.ClientConfig{
		APIKey:  os.Getenv("MY_API_KEY_PASTED_HERE"),
		Backend: genai.BackendGeminiAPI,
	})

	pdfBytes, _ := os.ReadFile("sber.pdf")

	print("\n\n\n")
	print(len(pdfBytes))
	print("\n\n\n")

	parts := []*genai.Part{
		&genai.Part{
			InlineData: &genai.Blob{
				MIMEType: "application/pdf",
				Data:     pdfBytes,
			},
		},
		genai.NewPartFromText("Summarize this document"),
	}
	contents := []*genai.Content{
		genai.NewContentFromParts(parts, genai.RoleUser),
	}

	result, _ := client.Models.GenerateContent(
		ctx,
		"gemini-2.0-flash",
		contents,
		nil,
	)

	fmt.Println(result.Text())
}

And I am getting this error all the time, have no idea how to fix it. Also tried with .txt file and I am getting same error. I am sure I did read file in to bytes but then it crashes when trying perform request with bytes payload.

Simple Text generation capabilities works fine without file upload payload.

Please help have no idea how to fix it.

pdf or txt I placed in project directory