In the current build of Malwarebytes for Mac, we are seeing a few instances where a user will receive an error message indicating a "Background service is offline".
If you are seeing the message shown in the screenshot above when you try to open the Malwarebytes app, there are a couple possible explanations for that. The first thing to check is to see if the system is preventing Malwarebytes for Mac from storing data in the system key chain.
To determine whether your system has an issue that is preventing Malwarebytes from storing data in the system keychain, open the Terminal app (found in the Utilities folder in the Applications folder). In the Terminal, enter the following command and press return:
ls -alO /Library/Keychains/System.keychain
(Copy that command and paste into the Terminal for the best results, to avoid typos.)
If the output that is displayed in the Terminal has the word "restricted" in it, like the following example, you have a problem with your system keychain.
-rw-r--r--@ 1 root wheel restricted 83556 Nov 16 2016 /Library/Keychains/System.keychain
If System.keychain is restricted
If the System.keychain file is "restricted," that means that your system keychain isn't writeable, not by any user on the system. You may also have seen other issues due to this, such as an inability to get your computer to remember wifi passwords.
Unfortunately, this is something that is not easily corrected. To fix the problem, follow these instructions to the letter! You should print these instructions or load them on another device so that you have them to refer to in the middle of the procedure.
Restart in recovery mode, by holding down command-R at startup. Once you're in recovery mode, go to the Utilities menu and choose Terminal. See the following screenshot:
In the Terminal window that opens, enter the following command. Be sure to enter it precisely as shown.
chflags norestricted /Volumes/*/Library/Keychains/*
Press return to execute the command. If you see an error message saying something like "No such file or directory" or "command not found," you made an error in typing the command. Review these instructions again and be sure you're entering it exactly as shown.
Now restart the computer normally, and Malwarebytes should be working normally.
If System.keychain is not restricted
If the output from the command to examine the System.keychain file does not contain the word "restricted," as in the following example, there's something else going on.
-rw-r--r-- 1 root wheel - 74244 Aug 30 10:45 /Library/Keychains/System.keychain
Most likely, in this case, either Malwarebytes for Mac did not get installed correctly, or something has removed, damaged or disabled components of Malwarebytes for Mac.
First, try restarting the computer. If that doesn't fix the problem, download a fresh copy of the Malwarebytes for Mac installer from here:
Run the uninstaller (the Remove Malwarebytes.pkg file) that is found on the Malwarebytes 3.dmg file to remove any possibly damaged copies of the software. Then run the Install Malwarebytes.pkg file to install the software again.