The App Engine Blobstore was introduced in 2008 as a way to store large objects in your App Engine apps. Since then, Google Cloud Platform has expanded and Cloud Storage has become the default way to store and serve arbitrary blobs. Beginning in 2014, we started recommending Cloud Storage instead of Blobstore.
On June 1, 2019, we will remove the Blobstore UI from the Google Cloud Platform Console. The Blobstore API and associated client libraries will continue to work and legacy blob serving will not be impacted, but you will no longer be able to manage legacy Blobstore objects through the GCP Console.
If your blobs are stored in Cloud Storage and you don't need the functionality provided by the Blobstore UI, you can start using the Cloud Storage object browser in the GCP Console instead of the Blobstore UI.
If your blobs are stored in legacy Blobstore, consider moving them to Cloud Storage with the App Engine Blobstore to Cloud Storage Migration Tool. Once moved, you can still use the Blobstore API to store and serve files stored in Cloud Storage, but you will also be able to manage the files with GCP-supported tools such as the Google Cloud client libraries and gsutil.
If you need the functionality provided by the Blobstore UI such as sorting, filtering, and deleting image URLs, you can run the open source Blobstore UI application. This is a separate App Engine module that runs alongside your existing application and surfaces the same functionality as the existing Blobstore UI. This application is not actively maintained by Google and does not have a Service Level Agreement (SLA).