# Square Reader (2nd Gen) Fails to Connect — SECURE\_CONNECTION\_TO\_SQUARE\_FAILURE / INTERNAL\_ERROR **URL:** \ **Category:** Questions\ **Tags:** reader-sdk, sdk, mobile-payments-sdk\ **Created:** [July 22, 2025, 3:23am UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301 "2025-07-22T03:23:17Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![slowslicing](https://avatars.discourse-cdn.com/v4/letter/s/3bc359/32.png) [@slowslicing](https://developer.squareup.com/forums/u/slowslicing)\ **Post date:** [July 22, 2025, 3:23am UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/1 "2025-07-22T03:23:17Z")
Hi, I’m encountering connection issues when using the Square Reader (2nd generation). During the connection process, the following errors appear: ```auto ReaderUnavailable(reason=SECURE_CONNECTION_TO_SQUARE_FAILURE) ReaderUnavailable(reason=INTERNAL_ERROR) ``` **Details:** - **Time (Pacific Time):** 2025-07-21 18:27:00 - **Location ID:** LSZEF1V47SWV7 - **Application ID:** sq0idp-g7k1G7BSi9k3DVNKzmWpkQ - **SDK Versions:** - `com.squareup.sdk:mobile-payments-sdk:2.3.0` - `com.squareup.sdk:mockreader-ui:2.3.0` I’m launching the built-in settings UI via: ```auto MobilePaymentsSdk.settingsManager().showSettings() ``` Shortly after this, the reader attempts to connect but fails with one of the above error messages. It then automatically disconnects or is removed. From what I can observe, the connection flow seems to be: 1. Bluetooth connected 2. Connecting to Square (I assume this means your servers) 3. Fails with `SECURE_CONNECTION_TO_SQUARE_FAILURE` or `INTERNAL_ERROR` 4. Reader is automatically removed I’m completely stuck at this point. Could someone help me understand what’s going wrong here? Thanks a lot in advance! ---
**Author:** ![Square-Dev-AI](https://sea1.discourse-cdn.com/square/forums/user_avatar/developer.squareup.com/square-dev-ai/32/2513_2.png) [@Square-Dev-AI](https://developer.squareup.com/forums/u/Square-Dev-AI)\ **Post date:** [July 22, 2025, 3:23am UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/2 "2025-07-22T03:23:29Z")
👋 I’m Square Dev AI, here to help answer your question! Based on the information you’ve provided, the following documentation will help answer your question: > **[Square Developer Documentation](https://developer.squareup.com/docs/reader-sdk/how-it-works)** > > Learn about the Reader SDK process flow and checkout flow and how they work. > **[Handling Errors](https://developer.squareup.com/docs/mobile-payments-sdk/ios/handling-errors)** > > Learn how to resolve errors in the Mobile Payments SDK for iOS. > **Additional Documentation** > > [Connect a Contactless Reader](https://developer.squareup.com/docs/reader-sdk/cookbook/contactless-reader) > [Reader SDK](https://developer.squareup.com/docs/reader-sdk/what-it-does) > [Pair and Manage Card Readers](https://developer.squareup.com/docs/mobile-payments-sdk/android/pair-manage-readers) If this documentation helped you find a solution, please check the box indicating that this reply solves the problem. Otherwise one of our Developer Advocates will provide additional assistance shortly. ---
**Author:** ![Bryan-Square](https://sea1.discourse-cdn.com/square/forums/user_avatar/developer.squareup.com/bryan-square/32/38_2.png) [@Bryan-Square](https://developer.squareup.com/forums/u/Bryan-Square)\ **Post date:** [July 22, 2025, 4:24pm UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/3 "2025-07-22T16:24:39Z")
Did you receive an email from Square regarding the status of your account? 🙂 ---
**Author:** ![slowslicing](https://avatars.discourse-cdn.com/v4/letter/s/3bc359/32.png) [@slowslicing](https://developer.squareup.com/forums/u/slowslicing)\ **Post date:** [July 23, 2025, 1:05am UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/4 "2025-07-23T01:05:45Z")
I don’t remember receiving it. I don’t see any issues in [Sign up for Square](https://developer.squareup.com/apps). ---
**Author:** ![Bryan-Square](https://sea1.discourse-cdn.com/square/forums/user_avatar/developer.squareup.com/bryan-square/32/38_2.png) [@Bryan-Square](https://developer.squareup.com/forums/u/Bryan-Square)\ **Post date:** [July 23, 2025, 4:48pm UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/5 "2025-07-23T16:48:00Z")
Okay, all looks good now. You’ll also need to add the [app signature](https://developer.squareup.com/docs/mobile-payments-sdk/android#application-signature) to connect to a reader. 🙂 ---
**Author:** ![slowslicing](https://avatars.discourse-cdn.com/v4/letter/s/3bc359/32.png) [@slowslicing](https://developer.squareup.com/forums/u/slowslicing)\ **Post date:** [July 28, 2025, 9:11am UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/6 "2025-07-28T09:11:30Z")
Thank you for your reply. However, I’m now encountering a new issue: **“This device is not supported. Please try another device.”** I tested the same reader on a colleague’s device, and it connected successfully. But on my vending machine’s Android device, I consistently receive this error message, which is quite confusing. Do you have any suggestions or solutions for this? Here is the log I captured: ```auto ReaderChangedEvent(change=CHANGED_STATE, reader=ReaderInfo( id='F8:44:77:49:42:22', model=CONTACTLESS_AND_CHIP, state=FailedToConnect(reason=[DeniedReason( uxHint=NO_SUGGESTED_ACTION, localizedTitle='Device Not Supported', localizedDescription='This device is not supported. Please try another device.' )]), status=ReaderUnavailable(reason=READER_NOT_SUPPORTED), serialNumber=444LS22207008231, name='Square Reader 8231', batteryStatus=BatteryStatus(percent=100, isCharging=true), firmwareVersion=402100, firmwarePercent=null, supportedCardEntryMethods=[], isForgettable=true, isBlinkable=true), readerSerialNumber=444LS22207008231 ) ``` The issue occurred at **Pacific Time: 2025-07-28 01:51:11**. ---
**Author:** ![Bryan-Square](https://sea1.discourse-cdn.com/square/forums/user_avatar/developer.squareup.com/bryan-square/32/38_2.png) [@Bryan-Square](https://developer.squareup.com/forums/u/Bryan-Square)\ **Post date:** [July 28, 2025, 4:53pm UTC](https://developer.squareup.com/forums/t/square-reader-2nd-gen-fails-to-connect-secure-connection-to-square-failure-internal-error/23301/7 "2025-07-28T16:53:01Z")
Is the device in developer mode? What is different about the tow devices? 🙂