From April 16th 2019 ArcGIS Online is only going to support TLS 1.2 (details available here).
If you use any ArcGIS Online functionality with LocatorHub then you may be affected. Potential touchpoints are:
ArcGIS Map Service Locators
ArcGIS Feature Service Locators
Coordinate Conversion via ArcGIS Online
Using LocatorHub Locators within ArcGIS Online via the ArcGIS Compatible REST endpoint
Regardless of whether you are using any of these touchpoints, it is good practice to ensure you are using or have the capability of using TLS 1.2. Some clients or database servers may enforce TLS 1.2 communication.
Ensuring TLS 1.2 compatibility
LocatorHub has supported TLS 1.2 from version 5.4 Service Pack 2. If you are using a version lower than this you will need to upgrade.
For all LocatorHub versions it will be necessary to make the following change to the LocatorHub web.config files (depending on which endpoint(s) you use):
If using LocatorHub standard REST/SOAP Endpoint and ArcGIS Compatible REST Endpoint:
If using LocatorHub SOAP Endpoint (deprecated)
If using LocatorHub Editable SOAP Endpoint
For the endpoint(s) in use, within the configuration file(s), locate the following line:
<compilation debug="false" targetFramework="4.0" />
Edit this line by changing 4.0 to 4.6.2, and add an additional line as below:
<compilation debug="false" targetFramework="4.6.2" />
<httpRuntime targetFramework="4.6.2" />
Save the change(s) and then restart IIS.
ArcGIS Online will be updated to enforce the use of TLS 1.2 on April 16th (previously scheduled for February)