Shopify Admin API returns 404 error when updating theme assets

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1

I’m working on injecting a JavaScript widget into the main theme file of a Shopify store through their Admin API.

theme_asset_endpoint = f"https://{store_name}/admin/api/2025-01/themes/{current_theme}/assets.json"
query_params = {"asset[key]": "layout/theme.liquid"}

# This works perfectly - returns 200
get_response = requests.get(theme_asset_endpoint, headers=auth_headers, params=query_params)
if get_response.status_code != 200:
    return {"error": "Cannot fetch theme file", "info": get_response.json()}

file_info = get_response.json().get("asset", {})
existing_content = file_info.get("value", "")

widget_code = f'<script type="module" src="{WIDGET_SOURCE}"></script>'
if widget_code in existing_content:
    return {"message": "Widget already exists in theme file"}

if "</body>" in existing_content:
    modified_content = existing_content.replace("</body>", widget_code + "\n</body>")
else:
    modified_content = existing_content + "\n" + widget_code

update_data = {"asset": {"key": "layout/theme.liquid", "value": modified_content}}
update_endpoint = f"https://{store_name}/admin/api/2025-01/themes/{current_theme}/assets.json"

# This fails with 404 error
put_response = requests.put(update_endpoint, headers=auth_headers, json=update_data)
print(put_response.status_code)  # Shows 404

The weird thing is that reading the asset works fine but updating it throws a 404. I’m using the same API version and authentication for both calls. The theme file definitely exists since I can retrieve it. Anyone know what might be causing this issue?

2

Check your permissions. You can read theme assets, but updating them needs write_themes scope in your API token. I hit this same issue - GET requests worked fine but PUT/POST failed with 404s because I only had read_themes permission. Make sure your API credentials have write permissions for theme changes. Also, some stores block theme API modifications with extra security settings, especially on live themes.

3

Check how you’re building the endpoint URL. Make sure your store_name variable has the full myshopify.com domain format. I hit this same issue when I forgot the .myshopify.com part in my store name variable. Also verify your auth headers have the right API version in the X-Shopify-Access-Token format. Sometimes you get a 404 when the auth context doesn’t match between GET and PUT requests, even though GET works fine. Log the exact URLs for both requests and compare them - you’ll probably spot the difference.

4

had the same prob before. shopify needs POST instead of PUT for asset updates. just swap requests.put with requests.post but keep the endpoint the same and it should work!