Object Storage Service:0048-00000114

Problem description

When you access an object in a browser using an OSS default domain name, the browser downloads the object instead of displaying a preview.

Cause

Starting December 22, 2025, at 10:00:00, OSS adds the following response headers when you use an OSS default domain name to access objects of specific Multipurpose Internet Mail Extensions (MIME) types in buckets created in the affected regions:

x-oss-force-download: true
Content-Disposition: attachment

Content-Disposition: attachment is a standard HTTP header that instructs the browser to download the content rather than display it inline. x-oss-force-download is an OSS-specific header added alongside it.

Affected regions

Buckets created in the following regions are affected:

• China (Ulanqab)

• China (Heyuan)

• China (Guangzhou)

• China (Nanjing - Local Region - Being Decommissioned)

Affected MIME types

• image/jpeg

• image/gif

• image/tiff

• image/png

• image/webp

• image/svg+xml

• image/bmp

• image/x-ms-bmp

• image/x-cmu-raster

• image/exr

• image/x-icon

• image/heic

Example

You have a bucket in the China (Guangzhou) region containing an object named test.jpg with a MIME type of image/jpeg. When you access test.jpg using the OSS default domain name:

GET /test.jpg HTTP/1.1

Because image/jpeg is an affected MIME type, OSS adds both headers to the response:

HTTP/1.1 200 OK
Content-Disposition: attachment
x-oss-force-download: true

The browser then prompts a download instead of displaying a preview.

Solution

Access the object using a custom domain name. When accessed through a custom domain name, OSS does not add the force-download headers, and the browser can display a preview normally.

For steps to bind a custom domain name to your bucket, see Attach a custom domain name.