Symantec Endpoint Protection (SEP) clients running version 14 RU1 cannot download Common Network Transport Library and Configuration (STIC) defintions from a version 14.2 Symantec Endpoint Protection Manager (SEPM).

debug.log
2019/06/01 14:18:00.620 [10576:8604] LuMan: Entering ApplyContent: {075551EC-66BD-4487-9E2E-40645AF6F8B0}, 190513038, 7, 190418025
2019/06/01 14:18:00.745 [10576:8604] LuMan: ApplyContent result: 0x00000000, DURESULT: 44
2019/06/01 14:18:00.745 [10576:8604] LUMan: Call to LueSupportedContent::Initialize returned success in ApplyContent.
2019/06/01 14:18:00.745 [10576:8604] SyLinkEventFunc - EVENT_LU_DOWNLOAD_COMPLETED: ApplyContent returned CMC_CONTENTUPDATE_ERROR(-536805375)
2019/06/01 14:18:00.745 [10576:8604] CAsyncHttpConnection::Close - Request: InternetReadFile; CtrlBlk: 0A467118 time: 0

SEP client system log
6/1/2019 14:18 302450688 2 Error An update for Common Network Transport Library and Configuration failed to install. Error: Content update general error (0xE0010001), DuResult: Authentication failed (44). LiveUpdate Manager

Sylink.log

06/01 14:18:00.620 [8604] [Content]<UpdateLUFileList:>Updating existing content update queue entry temp path from: to C:\Program Files (x86)\Symantec\Symantec Endpoint Protection\14.0.2415.0200.105\LiveUpdate\LUF{075551EC-66BD-4487-9E2E-40645AF6F8B0}1905130381904180257.TMP
06/01 14:18:00.620 [8604] [Content]<ProcessLUDownloadedFile>Processing content update: Moniker: {075551EC-66BD-4487-9E2E-40645AF6F8B0} Sequence: 190513038 Full: 0 Base Sequence: 190418025 Path: C:\Program Files (x86)\Symantec\Symantec Endpoint Protection\14.0.2415.0200.105\LiveUpdate\LUF{075551EC-66BD-4487-9E2E-40645AF6F8B0}1905130381904180257.TMP
06/01 14:18:00.620 [8604] <PostEvent> going to post event=EVENT_LU_DOWNLOAD_COMPLETED
06/01 14:18:00.745 [8604] <PostEvent> done post event=EVENT_LU_DOWNLOAD_COMPLETED, return=19
06/01 14:18:00.745 [8604] [Content]<ProcessLUDownloadedFile>SMC failed to process the content update: Error: 19
06/01 14:18:00.745 [8604] [Content]<UpdateLUFileList:>Updating existing content update queue entry: Moniker: {075551EC-66BD-4487-9E2E-40645AF6F8B0} Sequence: 190513038
06/01 14:18:00.745 [8604] [Content]<LUThreadProc>Failed to process content: Moniker: {075551EC-66BD-4487-9E2E-40645AF6F8B0} Target Seq: 190513038 State: 3 Error: 10

SEP 14 RU1 clients connected to and downloading defintions from a 14.2 SEPM.

Both 14 RU1 and 14.2 use the same moniker for STIC definitions however the two separate versions of SEP use separate certificate types to verify the authenticity of content.

This is resolved with an update to content where we now dual sign STIC definitions.