While session works overall, for one specific message we are getting checksum error.
Server is asking to resend the message and then fails with checksum validation.

20200729-08:03:12.189: Created session: FIXT.1.1:TEST1->TEST2
20200729-08:03:12.564: Configured socket addresses for session: [/host1:51641, /host2:51642]
20200729-08:03:12.845: MINA session created: local=/host3:60584, class org.apache.mina.transport.socket.nio.NioSocketSession, remote=/host1:51641
20200729-08:03:13.970: Initiated logon request
20200729-08:03:14.017: Setting DefaultApplVerID (1137=9) from Logon
20200729-08:03:14.048: Logon contains ResetSeqNumFlag=Y, resetting sequence numbers to 1
20200729-08:03:14.048: Received logon
20200729-08:19:47.751: Received ResendRequest FROM: 36 TO: 38
20200729-08:19:47.751: Error handling ResendRequest: failed to parse message (Expected CheckSum=70, Received CheckSum=71 in 8=FIXT.1.19=44635=AE34=3649=TEST152=20200729-08:19:46.14256=TEST215=JPY30=XOFF31=101.0780000032=5000000000.00000423=1487=1570=N571=FI-C-G5371117-20200729T091945.767574=9828=0854=01003=TAlmeKYeBA1041=0VBOND0V5371117V53711171430=O25011=ECHO25014=5000000000.0000025015=JPY552=254=229=4453=2448=LIOR75625447=N452=1448=LIOR75625447=N452=6354=1453=1448=FIO1CHULC69447=N452=17448=XOFF10=071): 8=FIXT.1.19=44635=AE34=3649=TEST152=20200729-08:19:46.14256=TEST215=JPY30=XOFF31=101.0780000032=5000000000.00000423=1487=1570=N571=FI-C-G5371117-20200729T091945.767574=9828=0854=01003=TAlmeKYeBA1041=0VBOND0V5371117V53711171430=O25011=ECHO25014=5000000000.0000025015=JPY552=254=229=4453=2448=LIOR75625447=N452=1448=LIOR75625447=N452=6354=1453=1448=FIO1CHULC69447=N452=17448=XOFF10=071

The issue is that both messages are exactly the same and checksum difference is always 1. Any idea what could be the root cause of the issue?

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