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Getting a strange message: "Sandbox: attempt to open unexpected file"

  • 2 replies
  • 1 has this problem
  • 4 views
  • Last reply by J B

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I run firefox from the command line in a terminal, and recently I have been seeing this set of messages in the term when I load various webpages:

Sandbox: attempt to open unexpected file /sys/devices/system/cpu/cpu0/cache/index2/size Sandbox: attempt to open unexpected file /sys/devices/system/cpu/cpu0/cache/index3/size Sandbox: attempt to open unexpected file /sys/devices/system/cpu/present Sandbox: attempt to open unexpected file /sys/devices/system/cpu Sandbox: unexpected multiple open of file /proc/cpuinfo

Mostly, there doesn't seem to be any loss of function related to this message. However, I have one anecdotal example of a forum website I have used in the past freezing on a blank screen at the same time these messages pop up in the term.

I can find no match for this particular message on the entire open internet. There is one near-match on bugzilla bug # Bug 1718493, but that is solved and done.

Any thoughts appreciated, thanks!

I run firefox from the command line in a terminal, and recently I have been seeing this set of messages in the term when I load various webpages: Sandbox: attempt to open unexpected file /sys/devices/system/cpu/cpu0/cache/index2/size Sandbox: attempt to open unexpected file /sys/devices/system/cpu/cpu0/cache/index3/size Sandbox: attempt to open unexpected file /sys/devices/system/cpu/present Sandbox: attempt to open unexpected file /sys/devices/system/cpu Sandbox: unexpected multiple open of file /proc/cpuinfo Mostly, there doesn't seem to be any loss of function related to this message. However, I have one anecdotal example of a forum website I have used in the past freezing on a blank screen at the same time these messages pop up in the term. I can find no match for this particular message on the entire open internet. There is one near-match on bugzilla bug # Bug 1718493, but that is solved and done. Any thoughts appreciated, thanks!

Modified by J B

All Replies (2)

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Could be a problem with the Widevine plugin if this happens when you visit pages that use DRM protected content.

  • 1712506 - Widevine try to access /proc/self/maps and /proc/net/unix

See also:

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I don't think it's any DRM issue since at least for this particular website which is just an old-school php forum, but those source files prompted me to discover the debugger and console windows you can open up in firefox and break on Exception (very cool), which eventually revealed that there is a server 500 error from the forum website i'm trying to access. So I guess that's nothing to do with firefox on my end despite the odd messages. I then tried the same page in google chrome, and it showed the 500 error directly on a served page. So thanks for the feedback, it did nudge me in the right direction.