In addition to publishing new web layers, you can use ArcGIS AllSource to overwrite existing web imagery layers to reflect changes to a GIS resource or its source data.
You can overwrite an existing web imagery layer if all of the following conditions are true:
- You are signed in to your ArcGIS organization with the account that owns the web imagery layer being overwritten. You cannot overwrite an existing web imagery layer owned by another member of your organization.
- The location of the web imagery layer being overwritten has not changed while the Overwrite Web Layer pane is open.
- The web imagery layer is not a hosted imagery layer.
Overwriting a web imagery layer is similar to sharing a web imagery layer. You can change most of the properties of a web imagery layer when you overwrite it, including properties of the imagery and configuration settings. You can't change the name of the service or its location (the service URL).
- Right-click the data for which you want to overwrite the web imagery layer, and click Overwrite Web Layer.
The Overwrite Web Layer dialog box appears.
- On the Overwrite Web Layer dialog box, browse to the location of the web imagery layer in your portal, select it, and click OK.
- Read the Overwrite Web Layer message and click OK to continue.
Caution:
If edits were made to the web layer, the edits will be overwritten.
The Overwrite Web Layer pane appears. On the General tab, under Item Details, the name of the web layer is displayed. This name can't be changed.
- Under the layer name, accept the Use the item description from the web layer default option or choose the Use the item description from the dataset option.
The default option preserves the item description of the current web layer. The other option overwrites it.
- Optionally, modify the information in the Summary and Tags fields.
The fields may be empty if you chose to use the item description from the table in the previous step. A summary and tags are required when sharing to an ArcGIS Enterprise 10.9 or earlier portal.
You can enter a maximum of 128 tags.
- Under Layer and Data Type, choose one of the following options:
- Reference registered data—Data that is registered with the server is referenced rather than copied to the server.
- Copy all data—All data is copied to the server.
- Optionally, under Sharing Level, change the settings:
- Owner—Only the owner (and organization members with privileges to view content owned by other members) can access the item. This is the default option.
- Organization—Share your content with all authenticated users in the organization. This option is available when you are signed in with an organizational account.
- Everyone (public)—Share your content with the public. Anyone can access and see it.
- Optionally, under Groups, select groups to which you belong to share your content with their members.
- Optionally, click the Configuration tab and change settings.
For more information, see Configure a web imagery layer.
- Under Finish Sharing, click Analyze
to review for potential problems. Errors and warnings are listed on the Messages tab. Right-click a message to open its help topic or take corrective action in the software. Errors
must be resolved before you can share your GIS resource. Resolving warnings 
is recommended but not required. - When the web layer is successfully published, click the Manage the web layer link at the bottom of the pane to access the web layer in your portal.
If the web layer will be drawn from cache built automatically on the server, the web layer may not be viewable while cache generation is in progress. Click Jobs
to view the cache status in the Job Status pane.