bcmwl: module cannot be inserted on Bionic: unknown symbol

[Brendan James]

On a Bionic Beaver system I installed via debootstrap I installed bcmwl-kernel-source. The installation went largely well, except it seemed to be experiencing a problem with loading the module. modprobe -a wl returns:

modprobe: ERROR: could not insert 'wl': Unknown symbol in module, or unknown parameter (see dmesg)

the lines in dmesg relating to wl are:

[ 10.892819] wl: loading out-of-tree module taints kernel.
[ 10.892822] wl: module license 'MIXED/Proprietary' taints kernel.
[ 10.892823] Disabling lock debugging due to kernel taint
[ 10.894423] wl: module verification failed: signature and/or required key missing - tainting kernel
[ 10.894455] wl: Unknown symbol cfg80211_inform_bss_frame_data (err 0)
[ 10.894470] wl: Unknown symbol cfg80211_scan_done (err 0)
[ 10.894488] wl: Unknown symbol cfg80211_disconnected (err 0)
[ 10.894506] wl: Unknown symbol wiphy_new_nm (err 0)
[ 10.894510] wl: Unknown symbol wiphy_register (err 0)
[ 10.894513] wl: Unknown symbol cfg80211_put_bss (err 0)
[ 10.894514] wl: Unknown symbol cfg80211_roamed (err 0)
[ 10.894517] wl: Unknown symbol cfg80211_gtk_rekey_notify (err 0)
[ 10.894521] wl: Unknown symbol cfg80211_ibss_joined (err 0)
[ 10.894526] wl: Unknown symbol cfg80211_michael_mic_failure (err 0)
[ 10.894529] wl: Unknown symbol ieee80211_get_channel (err 0)
[ 10.894533] wl: Unknown symbol wiphy_unregister (err 0)
[ 10.894537] wl: Unknown symbol cfg80211_get_bss (err 0)
[ 10.894549] wl: Unknown symbol ieee80211_channel_to_frequency (err 0)
[ 10.894553] wl: Unknown symbol cfg80211_report_wowlan_wakeup (err 0)
[ 10.894557] wl: Unknown symbol cfg80211_inform_bss_data (err 0)
[ 10.894559] wl: Unknown symbol ieee80211_frequency_to_channel (err 0)
[ 10.894563] wl: Unknown symbol cfg80211_connect_done (err 0)
[ 10.894565] wl: Unknown symbol wiphy_free (err 0)

I have tried rebooting after I get this error, just in case the kernel merely needed to be reloaded (doubted it would help but still worth a try), but alas that didn't help. If relevant I am using a Btrfs file system.

All the commands I have executed in it since the beginning of time (which was only a few hours ago, at most, so there isn't much to it) can be found here in its root bash_history file:

https://gist.github.com/22fdcbead4ce240230fa09f92a730a90

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[James Donald (jdonald)]

I get the same error on loading 'wl' (and the exact same 19 unknown symbols in dmesg) from installing bcmwl-kernel-source on Xenial.