here is the response with flag -v* Trying 17.154.66.159... * TCP_NODELAY set * Connected to sandbox.itunes.apple.com (17.154.66.159) port 443 (#0) * Initializing NSS with certpath: sql:/etc/pki/nssdb * CAfile: /etc/pki/tls/certs/ca-bundle.crt CApath: none * NSS error -5961 (PR_CONNECT_RESET_ERROR) * TCP connection reset by peer * stopped the pause stream! * Closing connection 0 curl: (35) TCP connection reset by peerand the next one* Trying 17.154.66.159... * TCP_NODELAY set * Connected to sandbox.itunes.apple.com (17.154.66.159) port 443 (#0) * Initializing NSS with certpath: sql:/etc/pki/nssdb * CAfile: /etc/pki/tls/certs/ca-bundle.crt CApath: none * ALPN, server accepted to use http/1.1 * SSL connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 * Server certificate: * subject: CN=buy.itunes.apple.com,OU=GNCS Traffic Management,O=Apple Inc.,L=Cupertino,ST=California,C=US,serialNumber=C0806592,incorporationState=California,incorporationCountry=US,businessCategory=Private Organization * start date: Mar 11 00:00:00 2020 GMT * expire date: Mar 12 12:00:00 2021 GMT * common name: buy.itunes.apple.com * issuer: CN=DigiCert SHA2 Extended Validation Server CA-3,OU=www.digicert.com,O="DigiCert, Inc.",C=US > POST /verifyReceipt HTTP/1.1 > Host: sandbox.itunes.apple.com > User-Agent: curl/7.53.1 > Accept: */* > Content-Length: 18903 > Content-Type: application/x-www-form-urlencoded > Expect: 100-continue > < HTTP/1.1 100 Continue * We are completely uploaded and fine < HTTP/1.1 200 Apple WebObjects < x-apple-jingle-correlation-key: V6NXK6GWZQRO4HE64QEUTSBLNY < x-apple-request-uuid: af9b7578-d6cc-22ee-1c9e-e40949c82b6e < pod: 100 < x-apple-translated-wo-url: /WebObjects/MZFinance.woa/wa/verifyReceipt < apple-tk: false < edge-control: no-store < edge-control: cache-maxage=0 < x-apple-lokamai-no-cache: true < cache-control: private < cache-control: no-cache < cache-control: no-store < cache-control: no-transform < cache-control: must-revalidate < cache-control: max-age=0 < itspod: 100 < x-webobjects-loadaverage: 10 < apple-seq: 0 < apple-originating-system: MZFinance < strict-transport-security: max-age=31536000 < x-frame-options: SAMEORIGIN < x-apple-orig-url: https://sandbox.itunes.apple.com/WebObjects/MZFinance.woa/wa/verifyReceipt < x-apple-application-site: SB < date: Tue, 07 Apr 2020 12:52:50 GMT < set-cookie: itspod=100; version="1"; expires=Thu, 07-May-2020 12:52:50 GMT; path=/; domain=.apple.com < set-cookie: mzf_in=990214; version="1"; path=/WebObjects; domain=.apple.com; secure; HttpOnly < set-cookie: mzf_dr=0; version="1"; expires=Thu, 01-Jan-1970 00:00:00 GMT; path=/WebObjects; domain=.apple.com < apple-timing-app: 4 ms < expires: Tue, 07 Apr 2020 12:52:50 GMT < x-apple-application-instance: 990214 < content-length: 16 < * Connection #0 to host sandbox.itunes.apple.com left intact

Even when I do request with curl's help like this:curl -X POST --data "password=" --data "receipt-data=" https://sandbox.itunes.apple.com/verifyReceiptfrom the same instance, first time I can get "curl: (35) TCP connection reset by peer" and second time I can get response 200.There can be 3 success requests then 1 or more errors in a row, that's why I don't think that this is the problem with the TLS certificates, because is certificates are wrong I will get "curl: (35) LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to sandbox.itunes.apple.com:443" error.Thanks!

`Since this is happening in only 80% of the cases, do you have multiple clients performing this validation?` - no, on our test environment we have only one client for receipt validation. On production we have multiple ones, but it's not happenning there, it happens only on sandbox and this is the issue for us because we can not understand what actually the problem is and we can not release new versions of appllications for iPhone 8 and others.And I'd like to notice that we get the "Connection reset" error only when trying to connect to https://sandbox.itunes.apple.com/verifyReceipt and not to https://buy.itunes.apple.com/verifyReceipt, this URL always responses with expected codes like 21007 or 21008 that says us that we are using test accounts.Thanks.

This is one of error logs I get```2020-04-03 01:02:36.287 ERROR 1 --- [pool-2-thread-1] o.s.s.s.TaskUtils$LoggingErrorHandler : Unexpected error occurred in scheduled task.org.springframework.web.client.ResourceAccessException: I/O error on POST request for "https://sandbox.itunes.apple.com/verifyReceipt":Connection reset; nested exception is java.net.SocketException: Connection reset at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:557) at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:502) at org.springframework.web.client.RestTemplate.postForEntity(RestTemplate.java:357) at com.stark.paytrack.apple.SpringHttpValidationStrategy.validate(SpringHttpValidationStrategy.java:66) at com.stark.paytrack.apple.SpringHttpValidationStrategy.validate(SpringHttpValidationStrategy.java:37) at com.stark.paytrack.subscription.AppleSubscriptionCreator.create(AppleSubscriptionCreator.java:70) at com.stark.paytrack.subscription.PlatformSubscriptionCreator.create(PlatformSubscriptionCreator.java:54) at com.stark.paytrack.subscription.DefaultRecurringSubscriptionUpdater.update(DefaultRecurringSubscriptionUpdater.java:60) at com.stark.paytrack.subscription.DefaultExpiredSubscriptionHandler.cleanupSubscription(DefaultExpiredSubscriptionHandler.java:61) at com.stark.paytrack.subscription.DefaultExpiredSubscriptionHandler.cleanupSubscriptions(DefaultExpiredSubscriptionHandler.java:103) at com.stark.paytrack.subscription.SubscriptionMonitor.checkForExpiredSubs(SubscriptionMonitor.java:42) at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:607) at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65) at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:473) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1152) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:622) at java.lang.Thread.run(Thread.java:748)Caused by: java.net.SocketException: Connection reset at java.net.SocketInputStream.read(SocketInputStream.java:197) at java.net.SocketInputStream.read(SocketInputStream.java:122) at sun.security.ssl.InputRecord.readFully(InputRecord.java:442) at sun.security.ssl.InputRecord.read(InputRecord.java:480) at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:936) at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1324) at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1351) at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1335) at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185) at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:167) at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:78) at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:52) at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:541) ... 22 common frames omitted```but I'm not sure it'll help, to that URL I send `receipt-data` and `password`.I remembered that it started happening approximatelly from the beginning of this year, I didn't change a code in this period.

No, I don't, all I have are logs concerning "connection reset" and sometimes "connect time out".But I'd like to notice that it mostly occurs in iPhone 8 and more rarely in 10, 11.Our whole payment procedure is the next:iPhone side - buy subscribsion, after payment went success, send receipt to the backend for further handling.Backend side - get receipt data and go to "https://buy.itunes.apple.com/verifyReceipt"/"https://sandbox.itunes.apple.com/verifyReceipt" to verify that receipt and then mark user as premium.Actually it happens durring testing with test accounts.Do you have any thoughts on why it can happen?