The Symantec Management Agent is unable to connect/register to a Task Server. While looking at the agent logs, the following error is noticed:

Operation 'Direct: Post' failed.
Protocol: HTTPS
Host: SMPserver.yourdomain.org:443
Path: /Altiris/ClientTaskServer/Register.aspx
Id: 962.6936
Error type: SMP Server error
Error code: The server is currently too busy to process the request (0x8004200C)
Error note: HTTP Status 200: 200 OK

Entry 1:

Operation 'Direct: Post' failed.
Protocol: HTTPS
Host: SMPserver.yourdomain.org:443
Path: /Altiris/ClientTaskServer/Register.aspx
Id: 962.6936
Error type: SMP Server error
Error code: The server is currently too busy to process the request (0x8004200C)
Error note: HTTP Status 200: 200 OK
Server HTTPS connection info:
   Server certificate:
      Serial number: 1e 00 02 51 4c 8f a3 ca 28 b5 c1 1e 01 00 00 00 02 51 4c
      Thumbprint: 24 34 8c e3 e7 ff ab 65 43 44 c0 00 2d 3c 94 3e 36 32 41 fe
   Cryptographic protocol: TLS 1.0
   Cipher suite: TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA_P256
   Cipher algorithm: AES
   Cipher key length: 256
   Hash algorithm: SHA1
   Hash length: 160
   Key exchange algorithm: ECDH_P256
   Key length: 256
-----------------------------------------------------------------------------------------------------
Date: 3/8/2019 9:05:30 AM, Tick Count: 68322010 (18:58:42.0100000), Size: 1010 B
Process: AeXNSAgent.exe (6936), Thread ID: 4620, Module: AeXNetComms.dll
Priority: 1, Source: NetworkOperation

Entry 2:
Failed to call web interface by url [https://SMPServer.yourdomain.org:443/Altiris/ClientTaskServer/Register.aspx?lastResort=true&resourceGuid=6e2727b3-1668-47c7-b856-15fbb152714a&crc=0008000000000D44], error [0x8004200C, IDispatch error #7692].
-----------------------------------------------------------------------------------------------------
Date: 3/8/2019 9:05:30 AM, Tick Count: 68322010 (18:58:42.0100000), Size: 483 B
Process: AeXNSAgent.exe (6936), Thread ID: 4620, Module: client task agent.dll
Priority: 2, Source: Client Task Agent

Entry 3:
Could not register using "https://SMPServer.yourdomain.org:443/Altiris/ClientTaskServer/Register.aspx"
-----------------------------------------------------------------------------------------------------
Date: 3/8/2019 9:05:30 AM, Tick Count: 68322010 (18:58:42.0100000), Size: 341 B
Process: AeXNSAgent.exe (6936), Thread ID: 4620, Module: client task agent.dll
Priority: 2, Source: Client Task Agent

ITMS 8.x

AppPool and Task Management Services where not responsive.
Also, this message can occur if the assigned Task Server is the SMP itself and it has only 100 computers or so under "Maximum computers to manage per Task Server" for the Task Service Settings (Site Management>Site Server Settings>Task Service>Settings) and that number has been reached and "Allow maximum computers to be exceeded if a computer cannot connect to any other server" is not enabled.

Try the following:

1. Recycle the Symantec Task Server AppPool under IIS Manager.
2. Restart the "Altiris Object Host Service" and "Altiris Client Task Data Loader" services.
3. Try again to register the client machine.

Note: If the issue persists or come back, check TECH247396