PROBLEM
In some instances, when attempting to update the settings of a hosted layer, the process fails and returns the following error message:
Error: Save wasn't successful. Try again later.
Additionally, more information can be viewed in the browser developer tools and network tab.
Depending on the cause, refer to one of the following solutions:
Add the ArcGIS Server domain URL in the Configuration field in the ArcGIS Portal Administrator Directory. Refer to Portal for ArcGIS: Restrict the portal's proxy capability for instructions.
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