After enabling the reverse proxy in Apache for Mac and Linux downloads (HOWTO85034), the Endpoint Protection Manager (SEPM) WebServer service (httpd.exe) frequently crashes.  

5/1/2019 2:16:45 PM    Application    Error    Application Error    sepm.testnet.work        1000    "Faulting application name: httpd.exe, version: 2.4.33.332, time stamp: 0x5c975237
Faulting module name: ntdll.dll, version: 10.0.14393.2485, time stamp: 0x5b84c286
Exception code: 0xc0000374
Fault offset: 0x000d9741
Faulting process id: 0x6c3c
Faulting application start time: 0x01d50048c08630e8
Faulting application path: D:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\apache\bin\httpd.exe
Faulting module path: C:\Windows\SYSTEM32\ntdll.dll
Report Id: 8ae333c8-1bc6-4400-acb3-dea67c89e1d2
Faulting package full name:
Faulting package-relative application ID:"   

The instructions for setting up the reverse proxy outline steps to modify the httpd configuration to disable AsyncSendFile for the reverse proxy's cache folder.  This configuration is needed to prevent crashes that can occur when the cache is updated with new files. 

Modify httpd.conf to only enable Asyncsendfile for the Inetpub/Content folder. 

Make the following changes to httpd.conf:

• Locate the following line, and add the character # to comment it out, as shown:
      #AsyncSendFile anydirectory
• Locate the following lines and remove the character # to uncomment them, and make the following change, where SEPM_Install is the actual path of your Symantec Endpoint Protection Manager installation (use forward slashes).
      AsyncSendFile givendirectory
    ForceAsyncSendFile "SEPM_Install/Inetpub/content"

These steps are also outlined in the following document:

Enabling Mac and Linux clients to download LiveUpdate content using the Apache web server as a reverse proxy