An example of this full error is:
12/4/2019 1:03:41 PM [Warning]: The remote server returned an error: (401) Unauthorized.
12/4/2019 1:03:41 PM [Response]: {"HttpStatusCode":"401","HttpResponse":"Invalid LocationKey"}
12/4/2019 1:03:41 PM [Response]: [ALOHA-124.9953]: <pos_users_search><HttpStatusCode>401</HttpStatusCode><HttpResponse>Invalid LocationKey</HttpResponse></pos_users_search>
This error can display for the following reasons:
- Aloha Store ID isn't matching between the POS and Punchh
- Firewall or whitelisting is blocking the Punchh End Points
- Changes on the Aloha end such as Aloha version upgrade without Punchh being updated as well
Here's how we can rule out these possibilities:
Aloha Store ID isn't matching between the POS and Punchh - In Punchh, the Store ID may be found from Settings>Locations> Find the location. The Store ID configured will be the first column on the left
If these do not match, the best thing to do is change the Aloha site number if possible. 
Firewall or whitelisting is blocking the Punchh endpoints. Please see out firewall requirements here: Aloha Firewall Setup
Changes on the Aloha end such as Aloha version upgrade without Punchh being updated as well - If your site was recently upgraded, or downgraded in Aloha versions, and Punchh was not informed, submit a ticket to support.punchh.com.
If the above options can be ruled out as not causing or resolving the issue, please perform an uninstall & reinstall of the Punchh application on the back of house computer.
After doing so, make sure to re-run the PunchhConf.exe to allow for any updates to information to be transferred down.