I am using Unity 2017.2.0f3. When I pause my game scene by use mouse click on pause button & play it frame by frame, it works OK. Instead, pause by use ctrl+shift+P keys down, an error will play once in console window at the time I press frame by frame button.

Assertion failed: Assertion failed on expression: '!dest.m_MultiFrameGUIState.m_NamedKeyControlList'
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

This would happens even in the new created empty scene!

Any help will be appreciated!

  • 2
    \$\begingroup\$ This sounds like an editor bug to log with the makers of the software. \$\endgroup\$
    – DMGregory
    Mar 30, 2018 at 12:14
  • \$\begingroup\$ Didn't read carefully enough to see you already had the full error message - my mistake. \$\endgroup\$
    – Pikalek
    Mar 31, 2018 at 1:37
  • \$\begingroup\$ Actually, my poor English writing skill made too many grammar mistakes in my expression to read it closely. That's not yours, Pikalek. :) \$\endgroup\$
    – xwcug
    Apr 2, 2018 at 1:33

1 Answer 1


This appears to be a known error.

The error report doesn't specifically include Unity 2017.2.0f3, but the patterns seems to fit. Since the error is not reproduced in 2018.1.0a4 and up, the best recommendation I can give is to upgrade / update to that version or later.

Here's the full error report:

Assertion failed error is thrown after pausing the game with a shortcut key and stepping one frame

Steps to reproduce:

  1. Create a new project
  2. Enter Playmode
  3. Press Ctrl+Shift+P or Cmd+Shift+P at the same time
  4. Press "Step" button

--Assertion failed error occurs

Error: "Assertion failed: Assertion failed on expression: '!dest.m_MultiFrameGUIState.m_NamedKeyControlList'UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)"

Reproducible with: 2017.2.0b5, 2017.2.1f1, 2017.3.0f2, 2018.1.0a3 Not Reproducible with: 2017.1.2p4, 2017.2.0a4 Regression introduced in 2017.2.0a4

Is not reproducible with 2018.1.0a4, a5, a6, a7

  • 1
    \$\begingroup\$ While annoying, upgrading/waiting for new versions is the "solution". I had this problem with 5.x and it disappeared on its own with some of the later 5. versions. \$\endgroup\$
    – Nikaas
    Mar 31, 2018 at 10:01
  • \$\begingroup\$ Thank you so much, Pikalek! I'll upgrade Unity to the bug fixed version. \$\endgroup\$
    – xwcug
    Apr 2, 2018 at 1:20

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