What is BCM42RLY?

The genuine BCM42RLY.sys file is a software component of Broadcom iLine10 by Broadcom.
The Broadcom iLine10 is a PCI Network Adapter, a hardware component used for connecting computers to a network. BCM42RLY.sys is a driver file that is required for the proper functioning of the Broadcom Network Adapter and should not be removed. The Broadcom Corporation is an American company that designs and develops fabless semiconductors which are mainly used in wireless and broadband communication. The company was founded in 1991 by Henry Samueli and Henry Nicholas, a professor-student pair from UCLA. Broadcom was acquired by Avago Technologies in 2016 and currently operates as its subsidiary. It currently generates over $8 billion in revenue and is currently listed in the Fortune 500. Broadcom is currently headquartered in Irvine, California, USA.

BcM42Rly stands for Broadcom M42 Relay Adapter Proxy Protocol Driver

BCM42RLY.sys is a Windows driver. A driver is a small software program that allows your computer to communicate with hardware or connected devices. This means that a driver has direct access to the internals of the operating system, hardware etc. The free file information forum can help you determine if BCM42RLY.sys is a Windows system file or if it belongs to an application that you can trust.

Run a free scan to check for BCM42RLY drivers in need of updating

BCM42RLY.sys file information

The process known as Broadcom iLine10™ PCI Network Adapter Proxy Protocol Driver or BCM42RLY belongs to software Broadcom iLine10™ PCI Network Adapter by Broadcom (

Description: BCM42RLY.sys is not essential for the Windows OS and causes relatively few problems. BCM42RLY.sys is located in the C:\Windows\System32\drivers folder. Known file sizes on Windows 10/8/7/XP are 18,424 bytes (50% of all occurrences) or 17,992 bytes. 
The driver can be started or stopped from Services in the Control Panel or by other programs. The program is not visible. There is no detailed description of this service. BCM42RLY.sys is not a Windows core file. BCM42RLY.sys appears to be a compressed file. Therefore the technical security rating is 16% dangerous, however you should also read the user reviews.

Recommended: Identify BCM42RLY.sys related errors

Important: Some malware disguises itself as BCM42RLY.sys, particularly when not located in the C:\Windows\System32\drivers folder. Therefore, you should check the BCM42RLY.sys process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

This problem manifests when I am running the ASUS drivers and Utility for my PCI Wireless Card (PCE-AC68). ASUS has acknowledged this issue and is working on a driver update for Windows 8.
After having installed Windows 10 on my Dell laptop inspiron 1545 I frequently (sometimes every 5 or 10 min) get the blue screen message (after a normal start-up): "DRIVER_RETURNED_HOLDING_CANCEL_LOCK(BCM42RLY.sys)". I had similar problems (0x0000011B) also before installing windows 10. On other times it will work properly for a whole day.
  Henk Herwig  

Summary: Average user rating of BCM42RLY.sys: based on 1 vote with 2 user comments. One user thinks BCM42RLY.sys is essential for Windows or an installed application. 2 users don't grade BCM42RLY.sys ("not sure about it").

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Best practices for resolving BCM42RLY issues

A clean and tidy computer is the key requirement for avoiding problems with BCM42RLY. This means running a scan for malware, cleaning your hard drive using 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the 6resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the 7DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the BCM42RLY.sys process on your computer, the following programs have proven to be helpful: ASecurity Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

BCM42RLY.sys [all]