Not a developer but have to soldier on, so advance apologies for any stupid questions:
I have just tried to link a ticketing app “Ticketor” to Square. They have their own POS and have provided a callback URL for the Square a card reader. I’ve found the Square Application ID and location ID on Ticketor, and have input the ticketor callback URL into the Web Callback URL on Square Developer POS API for my account. But when I try out the Ticketor POS, the error message below pops up on the Square App: “The web callback URl does not match the one in your application settings. Check your application’s Point of Sale API setting.”
I have asked the help desk on Ticketor and they said I need put it into the Square website as well? I have googled that, but the only help/article directs me to the Square Developer for callback url input. And there are not indications if I need to put it in the Square website, where in the website it is? Settings? Can someone advise and direct me on where else in Square I may need to put in the callback url?
Thank you in advance.
If this is our Point of Sale API you’ll need to configure the URL schemes in the Developer Dashboard. Once in the Dashboard you’ll want to go to Point of Sale API to configure the URL. 
Hi Bryan, Thanks for getting back.
Yes, I have put the Callback URL (provided by Ticketor) in the Developer POS API under the application I created. But I keep getting the same message on Square app that “the URL does not match”. Ticketor helpdesk suggested that I need to put the URL in both Square app and website, but other than in the Developer POS API, I don’t know where else they could mean?
May I ask what you mean by “reconfiguring” the URL scheme? Just wondering if there’s another step I need to do on the POS API IOS URL Scheme that Ticketor has not pointed out.
Is the Ticketor application correctly configured with the right production tokens? What application ID did you have to configure in Ticketor?
Yes, it should be correctly “configured”. I created the application in Square Developer, tested it in sandbox mode, turned it to production mode, and then copied & paste the Application ID, Access Token and Location ID into the Ticketor Payment processor page. When I tried to connect the Square card reader to the Ticketor POS, it goes via my ipad IOS Square app, and an error message comes up with “API Error: Your application is not configure for making calls from the web. Make sure you have a web callback url specified in the square developer portal”.
So Ticketor provides the web callback URL
https://www.ticketor.com/rotundatheatre/handlers/sales.ashx?Action=redirectSquare
I enter that into the Square Developer POS API, and try the connection again. And the error message on the Square app is now “API Error: The web callback URL does not match the one in your application settings. Check your application’s Point of Sale API settings.”
I have asked Ticketor helpdesk, and they said it’s because I have to enter the URL on both Square app and website. I have asked Square API Team and they said they’ve looked at my developer account and expect it to work.
Since now both Ticketor and Square are now saying that it’s not their system or the IDs or URL, I am trying to find out whether it is because I am not a developer and I have missed a step somewhere (coding etc.) where all developer knows to do, but I didn’t. Please do advice if there’s something else I have missed?
Hmm, Point of Sale API doesn’t have sandbox. Everything should be production. Do you have the link to the instructions they provided for setting up the integration?
Working in production not sand box.
These are the instructions ticketor gave me.
You can use any Square card readers that work with Android or iOS. These readers only work on Android and iOS.
Install the latest version of the Square Point of Sale application from the Google Play Store (Android) or the [Apple App Store]Then log in to the app and set your location or any other required settings. Use the same location as the one you set in payment processor settings.
If asked for callback URL, use: https://www.ticketor.com/rotundatheatre/handlers/sales.ashx?Action=redirectSquare
Right it won’t work in sandbox. That is expected.