Endpoint Protection client reports a HTTP error 400 when attempting registration with the manager

Products

• Endpoint Protection

Issue/Introduction

Endpoint Protection client appears offline with no green dot. A HTTP 400 error is observed on the client under Help | Troubleshooting > Server Connection Status
 
Enabling SECREG (linked article below) debug logging indicates too much Post Registration Data

09/10 11:56:28 [10804:9184] <CHttpReg::ProcessReq> Post Data ContentLength = 11872, Configured MaxPostDataLength = 8096.
09/10 11:56:28 [10804:9184] 4 Too much Post Registration Data.
09/10 11:56:28 [10804:9184] 192.168.1.100--FAILED

Environment

SEP 14.2 MP1 and newer

Resolution

Increase the size of the allowable client registration data, which can be configured through a registry key.

Registry location:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Symantec\Symantec Endpoint Protection\SEPM

Add DWORD MaxPostDataLength with decimal range of 8192 (min) to 131072 (max)

Essentially ((8 – 128) KB * 1024)

For the above example 12 KB * 1024 = 12288 to fit the blocked ContentLength of 11872 as noted in the error message above.

Restart SEPM Services to apply the change. 

Additional Information

Enabling SECARS and SECREG debugging for Endpoint Protection Manager