CM13 on Nexus 9: Any app that internally opens a webpage or otherwise uses System WebView crashes CyanogenMod 13 nightlies on Nexus 9 with Gapps installed.

I've been dealing with a persistent issue where any app that uses Android System WebView will crash. This means that any app that opens a webpage internally or otherwise tries to render HTML-based content internally (e.g. Email) will crash, rendering a large number of apps unusable.

Installing and updating WebView from Google Play does not help. In fact, it seems that the system is not using the downloaded WebView at all as there is no indication that the WebView app had ever opened at all.

An example error generated when this happens is as follows:

*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Build fingerprint: 'google/volantis/flounder:6.0.1/MMB29K/2419427:user/release-keys'
Revision: '0'
ABI: 'arm64'
pid: 12135, tid: 12667, name: RenderThread  &gt;&gt;&gt; com.android.email &lt;&lt;&lt;
signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
Abort message: '[FATAL:gl_fence_egl.cc(65)] Check failed: g_ignore_egl_sync_failures. 
'
    x0   0000000000000000  x1   000000000000317b  x2   0000000000000006  x3   0000000000000000
    x4   0000000000000000  x5   0000000000000001  x6   0000000000000000  x7   0000000000000000
    x8   0000000000000083  x9   0000007f7581a4bd  x10  0000007f7581a470  x11  0000007f7581a772
    x12  0000007f7581a4bc  x13  0000000000000054  x14  0000007f7a78c4f8  x15  0000007f8f772aa8
    x16  0000007f8f7646a0  x17  0000007f8f726b6c  x18  0000007f8f772a98  x19  0000007f7581c510
    x20  0000007f7581c450  x21  0000000000000000  x22  0000000000000006  x23  0000007f7581ad38
    x24  0000007f7ad78000  x25  00000000000005db  x26  0000007f7adab930  x27  0000007f7ac2b0f0
    x28  0000007f7581b14c  x29  0000007f7581a7b0  x30  0000007f8f724308
    sp   0000007f7581a7b0  pc   0000007f8f726b74  pstate 0000000020000000

backtrace:
    #00 pc 000000000006bb74  /system/lib64/libc.so (tgkill+8)
    #01 pc 0000000000069304  /system/lib64/libc.so (pthread_kill+68)
    #02 pc 00000000000211e0  /system/lib64/libc.so (raise+28)
    #03 pc 000000000001b980  /system/lib64/libc.so (abort+60)
    #04 pc 00000000006e0bc0  /data/app/com.google.android.webview-2/lib/arm64/libwebviewchromium.so


Any ideas?
The internal graphics driver was out of date. Updating the vendor image solved the problem. Updating also fixed a non-working camera.
CyanogenMod ROMs do not provide updated device-specific drivers (&quot;vendor&quot;), baseband firmware (&quot;radio&quot;; for cellular devices only), or bootloaders. These are stored on their own partitions and must be flashed manually at the fastboot bootloader. To do so, download the latest stock system image, extract it, and flash the applicable files:
fastboot flash bootloader &lt;bootloader-image&gt;
fastboot flash vendor &lt;vendor-image&gt;
fastboot flash radio &lt;radio-image&gt;


Update: An official CyanogenMod blog post states:

Nexus devices now ship with a large portion of their proprietary code in a vendor partition on the device itself. This is not something CM’s installation will update for you. If your vendor partition doesn’t match with the CM build, you will be met with an error on boot up that the system is potentially corrupted. To prevent this message (and ensure things like camera function), you should make sure you are on the latest available vendor image for your device. Vendor images can be found in the stock Nexus factory images provided by Google here. Extract the latest available zip and flash the vendor image through your bootloader with ‘fastboot flash vendor vendor.img’.

The error at boot-up looks like this:

Android System
There's an internal problem with your device. Contact your manufacturer for details.