Category: WSERV

The window server runs continuously and brings the machine down if it crashes, so it cannot panic its own thread when it detects an error in one of its client’s requests. Instead it panics the client’s thread using CSession::Panic(). These panics have a category of WSERV.

These panics are defined in the enumeration TClientPanic in w32cmd.h.

Note that some panics are raised in debug builds only.

1	Out of range opcode. The client has sent a request opcode that wasn’t recognised. Each server-side object can only handle some of the requests defined in the window server, and if the request isn’t recognised, this panic is raised. Clients would normally only get this is if they bypass the normal Window Server API.
2	Invalid command buffer. A corrupt buffer of requests was discovered by the server. This is raised when the buffer itself is noticeably broken, and not when the commands in it are wrong.
3	Invalid handle. The server couldn’t find the target object for a request in the handle index. This can be raised when a command is sent to the handle for a window that has been closed, for example.
4	A handle whose value was NULL was detected. For example, when Constructing one of the subclasses of the client-side `RWindowBase` with a client handle argument of NULL. On the server side, a `TWsClCmdCreateWindow` with a client handle field of `NULL` passed as argument to `CWsClientWindow::ConstructL()` will raise this error.
5	A single drawing command was too big to fit into the client-side buffer. The size of the buffer may be increased. See `RWsSession::SetBufferSizeL()` and `RWsSession::SetMaxBufferSizeL()`.
6	Invalid window handle. A handle which should have referred to a window of a particular type referred to a window of another type, or the object index didn’t recognise the handle. On the server side, this panic is ultimately raised by `CWsClient::HandleToWindow()` and `CWsClient::HandleToClientWindow()` during handle conversions.
7	Invalid bitmap handle. A corrupt bitmap handle was encountered. This is a common panic uncovered when a bitmap handle refers to nothing, or to a server-side object that isn’t a bitmap. Also: In response to an `EWsGcOpUseBrushPattern` request if the bitmap parameter couldn’t be used. On the client side, `CWindowGc::UseBrushPattern()` sends this request. In response to an `EWsSpriteOpAppendMember` request when the bitmaps for the sprite member can't be created on the server side. On the client side, `RWsSpriteBase::AppendMember()` sends this request. Any failed attempt to duplicate a supplied bitmap.
8	Event read already outstanding. `RWsSession::EventReady()`, `RWsSession::RedrawReady()`, or `RWsSession::PriorityKeyReady()` was called again when an event read was already outstanding, i.e.. when an event was waiting to be delivered by the window server.
9	Attempted to use a non-active graphics context. A drawing request was sent to a graphics context when the context was not active. On the server side, this panic is raised by `CWsGc::CommandL()` on all requests received when the context isn’t active except `EWsGcOpActivate`, `EWsGcOpDeactivate`, `EWsGcOpFree`, and `EWsGcOpTestInvariant`.
10	Attempted to activate an already active graphics context. On the server side, this is raised by `CWsGc::Activate()` as a response to a `EWsGcOpActivate` request. The request is sent by the client-side method `CWindowGc::Activate()`.
11	Window already active. An attempt was made to reactivate an active window. The request is sent by the client-side method `RWindowBase::Activate()`. On the server side, this panic is raised by `CWsClientWindow::Activate()` in response to an `EWsWinOpActivate` request.
12	Already inside a begin/end redraw pair. A begin-redraw window request was made when the window had already begun redrawing. Begin-redraw messages are paired with end-redraw messages, and ordering is important. Invoking `RWindow::BeginRedraw()`, then `RWindow::BeginRedraw()` again before the corresponding `RWindow::EndRedraw()` raises this panic. On the server side, this panic is raised if an `EWsWinOpBeginRedraw` request is sent twice before the closing `EWsWinOpEndRedraw`.
13	Invalid font handle. On the client-side is raised if `CWindowGc::UseFont()` is called with an invalid font handle. On the server side, `CWsGc::SetGcAttribute()` raises this error in response to an `EWsGcOpUseFont` request.
14	Printing with no active font. A command to draw text to a window was sent to a graphics context when no font was set. Any of the overloads of `CWindowGc::DrawTextVertical()` or `CWindowGc::DrawText()` might cause the panic to be raised; the font should be set using `CWindowGc::UseFont()` first. On the server side, this panic is raised by `CWsGc::DoDrawCommand()` in response to any of the requests to display text defined in `TWsGcOpcodes`.
15	Attempted to set an invalid text cursor type, see `RWindowGroup::SetTextCursor()`. Valid types are defined in the `TTextCursor` struct.
16	A drawing command was sent to a graphics context active on a group window.
17	Not used.
18	Not used.
19	Attempted to use a patterned brush when the pattern bitmap has not yet been set — `UseBrushPattern()`.
20	Not used.
21	Attempted to do a client destroy function on an illegal handle. A client tried to destroy or cancel a server-side object by its handle on an unrecognised handle, or on a handle of the wrong type for the operation. This panic may be caused by the `RWindowGroup::CancelCaptureKeyUpAndDowns()` or `RWindowGroup::CancelCaptureKey()` methods. These correspond to the `EWsWinOpCancelCaptureKeyUpsAndDowns` and `EWsWinOpCancelCaptureKey` server requests. In this case, the panic means that there is no such capture key object in existence in the target window group.
22	Panic from the Anim DLL. An animation DLL tried either changing its default or next timing interval when its timing mode was set to `ESyncNone`, or activating a graphics context when the context was already activated. There are a variety of other reasons why this panic might be raised, all which are Anim DLL related. The Animation writer can also cause functions raise this panic.
23	Invalid Anim object handle. A null animation handle was detected in the server on receipt of an animation command, possibly because the relevant animation has been deleted. This panic may be raised by a subclass of `RAnim` calling `RAnim::Command()` or `RAnim::CommandReply()`. On the server side, the `EWsAnimDllOpCommandReply` and `EWsAnimDllOpCommand` requests can raise this panic in `CWsAnimDll`.
24	Leave from a non-leaving animation function. Code in an animated DLL called by the server invoked `Leave()`. Animated DLL code is provided by the client and run by the server, so unhandled leaves are trapped and the notification is passed on as a client panic.
25	Not used.
26	Not used.
27	Not used.
28	Inconsistent polygon or polyline data was supplied. For example when restarting without finishing an old polygon.
29	A client attempted to set a negative shadow height. This panic is caused by a call to `RWindowBase::SetShadowHeight()` with a negative argument. On the server side, `CWsClientWindow::CommandL()` raises the panic in response to an invalid `EWsWinOpSetShadowHeight` request.
30	Not used.
31	The client tried to construct a window with an invalid redraw type. The valid redraw types defined in the enumeration `TWinTypes` of `w32cmd.h`. On the server side, this panic is raised by `CWsClientWindow::ConstructL()` in response to an initialisation message containing an invalid redraw type.
32	A server-side redraw region is almost certainly corrupt. This panic is raised when an `EWsWinOpGetInvalidRegion` is received by a `CWsRedrawMsgWindow` with a `TInt` parameter of zero or less.
33	The client failed to provide a reply buffer to a server-side function when one was needed. All server-side functions that need more space for their reply than a `TInt` use the client’s reply buffer. If the client fails to provide space for such replies, this panic will be emitted. This panic is raised by `CWsClient::ReplyBuf()` when `CWsClient`’s reply buffer is null.
34	Not used.
35	A client passed an invalid or unrecognised corner type or flag. This panic is raised in response to a client call to `RWindowBase::SetCornerType()` when specifying inconsistent or non-existent flags. Valid flags are masked by `ECornerTypeMask`, and recognised types are defined in `TCornerType`. These are all defined in `w32std.h`. The server raises this panic as a response to `EWsWinOpSetCornerType` request with an undefined corner type or an unrecognised flag in its parameters.
36	The server was asked to update a region of a backed-up window which has not had MaintainBackup called on it. A client-side call to either form of `RBackedUpWindow::UpdateScreen()` may raise this panic. On the server side, the panic is raised in response to an `EWsWinOpUpdateScreenRegion` or `EWsWinOpUpdateScreen` request when not maintaining a full backup of a backed-up window.
37	Panic raised when it was not possible to read or write data to the client thread. The data is usually contained in a descriptor.
38	The client attempted to access a sprite after the sprite's window was destroyed. Note that pointer cursors are implemented as sprites.
39	A client requested event data without having received an event telling it that the data was ready.
40	The mask for a sprite is smaller than the sprite’s bitmap. A mask is permitted to be larger than its bitmap.
41	Bad sprite handle. A null sprite handle was encountered, or a handle which was supposed to refer to a sprite referred to something else. The client-side methods `RWindowTreeNode::SetCustomPointerCursor()` and `RWsSession::SetSystemPointerCursor()`, amongst others, can cause this panic to be raised; they correspond to the server requests `EWsWinOpSetCustomPointerCursor` and `EWsClOpSetSystemPointerCursor`.
42	A client attempted to set or clear a system pointer cursor without first owning the list of system pointer cursors. `RWsSession::SetSystemPointerCursor()` and `RWsSession::ClearSystemPointerCursor()` can raise this panic. See also `RWsSession::ClaimSystemPointerCursorList()` and `RWsSession::FreeSystemPointerCursorList()`. The server requests which can raise this panic are `EWsClOpSetSystemPointerCursor` and `EWsClOpClearSystemPointerCursor`.
43	A client attempted to enable a pointer move buffer when none was allocated. `RWindowBase::EnablePointerMoveBuffer()` can cause this panic to be emitted; the corresponding server request is `EWsWinOpEnablePointerMoveBuffer`.
44	Raised in response to commands that send a string, when the string has been incorrectly stored in the command buffer.
45	Not used.
46	An invalid call or request parameter was detected by `CWsPassword`. This can be caused: By `RWindowBase::PasswordWindow()` sending an `EWsWinOpPasswordWindow` server request whose password mode parameter is not recognised. By an attempt to cancel the password window by a client which doesn’t own the window. By `RWsSession::PasswordEntered()` sending a `EWsClOpPasswordEntered` server request when no password window has been set, or when the client does not own the password window. Valid password modes are defined in `TPasswordMode` of `w32std.h`.
47	An invalid compute mode was sent to the window server. On the client side, `RWsSession::ComputeMode()` can do this, the window server request is `EWsClOpComputeMode`. Valid compute modes are defined in the enumeration `RWsSession::TComputeMode`, which is declared in `w32std.h`.
48	A client attempted to set the display mode of a backed-up window. This can be done with `RWindowBase::SetRequiredDisplayMode()` or the `EWsWinOpRequiredDisplayMode` server request.
49	A client attempted to get a message when has not been signalled in the server. This panic can be raised on a client thread calling `RWindowGroup::FetchMessage()` or sending the `EWsWinOpGetMessageSize` or `EWsWinOpGetMessage` messages.
50	A client tried to send a second initialisation message, i.e. to call `RWsSession::Connect()` twice.
51	A client attempted to send a message without specifying a target window. This can be raised, for example, in response to `RWsSession::RequestOffEvents()`
52	A client attempted to perform and operation on a window that has had its parent or ancestor deleted. An operation which might raise this panic could be setting the window size, position or extent. Introduced in v5.1
53	A client attempted to reset a window group’s default owning window. For example, by calling the function `RWindowGroup::DefaultOwningWindow()` twice on the same window group. This is only raised in debug builds.
54	A client attempted to perform an operation on an invalid screen mode. For example, if the client called the functions `CWsScreenDevice::GetScreenModeSizeAndRotation()` or `CWsScreenDevice::SetScreenMode()` with an illegal index. Introduced in v5.1
55	A client attempted to set an invalid screen enforcement mode. The valid screen mode enforcement modes are defined in `TScreenModeEnforcement`. Introduced in v5.1
56	A client specified an event type which was not a pointer event, when this is what was required by the operation. e.g. `RWindowGroup::SimulatePointerEvent()`. Introduced in v5.1
57	A client attempted to specify a screen rotation or orientation that is not allowed. Each screen size mode has a list of allowed rotations. Introduced in v5.1
58	A client attempted to call a function that can only be called on a top level client window on a lower level window. A top level client window is a window with a window group as a parent, e.g. `RWindowBase::MoveToGroup()`. Introduced in v6.0
59	A client attempted to use a `RDirectScreenAccess` object's member functions in the wrong order. Introduced in v7.0
60	The handle to a window server resource is already in use (debug builds only). Introduced in v7.0
61	An attempt was made to set a custom text cursor (using `RWindowGroup::SetTextCursor()`) but the cursor's type was not recognised. Introduced in v7.0s.
62	An attempt was made to set a custom text cursor (using `RWindowGroup::SetTextCursor()`) whose alignment value is invalid. For valid alignment values see the `TCustomTextCursorAlignment` enumeration in class `RWsSession`. Introduced in v7.0s.
63	An attempt was made to set a custom text cursor (using `RWindowGroup::SetTextCursor()`) that does not have any sprite members set. Introduced in v7.0s.
66	An attempt was made to call an event API without specifying the SwEvent capability, such as `RWsSession::SimulateKeyEvent()`, `RWindowGroup::SimulatePointerEvent()`. Introduced in v8.1.