Debug

1 - I am encountering a problem with a TWAIN Device.

If you have a problem with a TWAIN device we recommend trying the following things:

Get the latest version of the scanner's drivers from the manufacturer's web site and re-install them.
Get the latest TWAIN Data Source Manager files from www.Twain.org and put them in your windows directory (NOT the windows\system directory). Also, make sure you don't have older versions of those DLLs or EXEs anywhere else in your path.
Make sure you have the latest version of TwainPRO™.
If you still have a problem with a particular scanner, let us know, but remember, not all TWAIN capabilities are supported by all devices and there are TWAIN drivers out there that have bugs in them and are not fully TWAIN compliant.

2 - It appears that setting a capability has no effect on the scanned image.

There are a couple of reasons this issue may be occurring:

Resolution 1:

Please make sure that you call OpenSession before setting the capabilities. For example:

Example	Copy Code
ICAP TwainPRO1.SelectSource TwainPRO1.ShowUI = False TwainPRO1.OpenSession

Resolution 2:

Not all TWAIN devices support all TWAIN capabilities. Because of this, you must check to see if a TWAIN capability is supported by your device before setting it.

To do this, TwainPRO™ provides a method called IsCapabilitySupported, which will return True if the capability is supported and False if not. Note that if a scanner supports a capability, it might only support getting it and does not necessarily support setting it.

Below is an example of how to check this property:

Example	Copy Code
if (twainDevice.IsCapabilitySupported(Capability.IcapPixelType) == true) { // If the capability is supported this code will be executed. }

3 - I want to drive a scanner via the Kofax VRS TWAIN driver without using the Kofax TWAIN UI.

Kofax VirtualReScan (VRS) works best with an ISIS driver and only supports some scanners with TWAIN drivers. Documentation for Kofax VRS can be found at www.kofax.com.

Error Codes

This section includes error codes and extended error codes.

7000	TwainException	TWAIN error, check ConditionCode & ConditionDescription properties. The Data Source has returned an error. Check the ConditionCode and ConditionDescription properties to see if the Data Source has returned an error code.
7001	TwainDllLoadException	Can't find or load TWAIN DSM (TWAINDSM.dll, Version 2). The 32-bit version should be installed in the SYSTEM32 directory on native 32-bit Windows systems. On native 64-bit Windows systems, the 32-bit version should be installed in the SYSWOW64 directory. The latest version can be found at www.twain.org. Possible causes: The file is missing. The file is in use by another application.
7002	FileOpenException	TwainPRO can’t open an existing TIFF file to append pages. Possible causes: The file is open in another control or application. The file is read-only
7003	OutOfMemoryException	TwainPRO was unable to allocate memory for the requested operation. Possible causes: The image being transferred is too large to fit in memory. Too many applications are open.
7004	OperationCancelledException	The user cancelled the requested operation. Possible causes: The user clicked the cancel button on the source selection dialog invoked by the TwainDevice.SelectSource method.
7005	FileCreateException	TwainPRO was unable to create the file specified in the ScannedImage.SaveFile method. Possible causes: The drive or path specified doesn’t exist. The file exists and is in use by another application. No file extension or an invalid file extension was specified.
7006	FileWriteException	An error occurred while TwainPRO was attempting to save a file to the path specified in the ScannedImage.SaveFile method. Possible causes: The drive or path became invalid during the write. This can occur if the drive is a network drive. The disk is full.
7007	UnsupportedFileFormatException	A file extension for specified for a file type not supported by TwainPRO. Supported file types are: BMP, JPEG, ePIC, and TIFF.
7008	StringIsTooLongException	A string with too many characters was set to a TwainPRO property. Possible causes: The application identity properties can accept a maximum length of 32 characters. The SaveOptionsPic.Password property can accept a maximum length of 8 characters.
7009	ValueOutOfRangeException	The value is out of range. An invalid value was set to a TwainPRO property. Possible causes: Many TwainPRO properties can only accept values in a specified range. For example, the SaveOptionsJpeg.Luminance property must be in the range 0-255.
7010	ImageNotAvailableException	No image is available for the requested operation or an unsupported DIB format was returned in response to a StartSession. Possible causes: The ScannedImage.ToHdib property has already been read. The ScannedImage.SaveFile method was invoked after the hDIB property was read.
7011	PegasusFilesNotInstalledException	The required Accusoft dll file(s) are missing. Possible causes: Accusoft dll files are required when saving JPEG, ePIC, or TIFF files. They are listed in the dependencies section.
7012	InternetFilesNotInstalledException	The required Internet dll file(s) are missing. Possible causes: The following files are not present on the system. These files are not shipped with TwainPRO and are not needed unless an FTP address is specified in the ScannedImage.SaveFile method. These files are included with other software such as Internet Explorer, and if the machine has a TCP/IP connection, it should have these files: wininet.dll urlmon.dll
7013	FtpTransferException	An error occurred trying to FTP an image. Possible causes: The machine is not currently connected to a network. The FtpOptions.NetworkCredentials property settings are not correct for the requested host specified in the ScannedImage.SaveFile method. The host and or path specified in the ScannedImage.SaveFile method doesn’t exist. The path was not specified in the ScannedImage.SaveFile method. A fully qualified URL containing both the servername and file path must be specified. For example, "http://ftp.myserver.com/ftp/public/test.jpg" contains both the server and file information, but "http://ftp.myserver.com" does not.
7014	SequenceException	Illegal operation for current Source Manager or Source state. The requested action cannot be performed in the current state of the TWAIN session. Possible causes: Certain methods and properties are only valid during certain states. For example, the DataSourceCollection is invalid unless the TwainDevice.OpenDataSourceManager method was called to open the Data Source Manager.
7015	IndexOutOfRangeException	The requested index was out of range for the property array.
7016	InvalidPropertyException	A property was set or queried that was not valid for the current capability type. Please see the Negotiate Capabilities section for more information.
7017	ClipboardException	An error occurred trying to open the clipboard with the ScannedImage.CopyToClipboard or ScannedImage.CutToClipboard method. Possible causes: Another application has the clipboard open.
7018	InternalErrorException	Internal error.
7019	InvalidBitDepthException	Invalid image resolution for selected file format or an unsupported bits per pixel was returned from a StartSession. Possible causes: Tried to save a 1-bit or Black and White image to a jpg or pic file.
7020	PropertyOrMethodNotAvailableException	The property or method requested is not currently available. Possible causes: This exception may occur when the requested capability function is not available for the current capability. For example, this may occur for the TwainDevice.GetCapabilityConstantDescription() method when using an Advanced Capability.
7021	CompressedImageNotAvailableException	No compressed image is available for the requested operation or an unsupported compressed image format was returned in response to a StartSession. Possible causes: The requested Source compression may not be available on the device. Or it may occur if either of the deprecated ScannedImage.SaveFile() or ScannedImage.SaveStream() methods is used.
7022	DataSourceInvalidOperationException	The Data Source performed an operation that caused an exception. This error is a critical error. If this error is received then the application should be terminated immediately. No other TwainPRO calls should be made after this error is received. This does give the application the chance to do any non-TWAIN clean-up processing as well as inform the user that a critical error has occurred. Possible causes: The Data Source TWAIN driver executed an illegal operation, such as an illegal memory access, a divide by zero, etc.
7023	InvalidLicenseException	Invalid license.
7024	TiffTagNotFoundException	TIFF tag not found.
7025	TiffTagItemNotFoundException	TIFF tag item not found.
7026	FileReadException	Error reading file.
7027	LoadSettingsException	An error occurred while initializing the settings file reader system.
7028	LoadSettingsException	An error occurred while terminating the settings file reader system.
7029	LoadSettingsException	An error occurred when opening the settings file.
7030	LoadSettingsException	The TwainDevice Name attribute was not found in the settings file.
7031	LoadSettingsException	Settings for the current scanner were not found in the settings file.
7032	LoadSettingsException	The Capability Enum attribute was not found in the settings file.
7033	LoadSettingsException	Invalid file name.
7034	FileNotFoundException	The specified file was not found for the current LoadOptions operation.
7035	LoadSettingsException	The specified path of the filename was not found.
7036	LoadSettingsException	The file is in use by another process and cannot be opened.
7037	IOException	The file close operation could not be completed.
7038	IOException	The file reset operation could not be completed.
7039	LoadSettingsException	The Capability Type attribute was not found in the settings file.
7040	CapabilityNotSupportedException	The Capability is not supported.
7101	TwainDllLoadException	Can't find or load TWAIN DSM (twain_32.dll, Version 1) in the Windows directory. The latest version can be found at www.twain.org.
7102	TwainDllLoadException	Can't find or load any version of the Twain Data Source Manager. The latest version can be found at www.twain.org.
7103	TwainDllLoadException	On native 64-bit systems, Version 1 of the DSM (twain_32.dll) can't be used, you must use at least Version 2 (TWAINDSM.dll).
7104	TwainDllLoadException	Can't find or load TWAIN DSM (TWAINDSM.dll, Version 2). The 64-bit version of TwainDSM.dll should be installed in the SYSTEM32 directory. The latest version can be found at www.twain.org.
7105	ArgumentException	TwainDevice.DataSourceManagerVersion can't be set to None, please choose a valid version to use.
7106	SourceCompressedImageOnlyException	The image was compressed directly in hardware by the source and not by TwainPro, please use ScannedImage.SaveSourceCompressedImageToFile() or SaveSourceCompressedImageToStream() to save the scanned image.
7107	TwainProCompressedImageOnlyException	Hardware compression isn't available so only TwainPro can compress the image, please use ScannedImage.SaveToFile() or SaveToStream() to save the scanned image.
7108	ValueOutOfRangeException	The JPEG Luminance value is out of range. It should be within the range of 0 to 255.
7109	ValueOutOfRangeException	The JPEG Chrominance value is out of range. It should be within the range of 0 to 255.
7110	ValueOutOfRangeException	The JPEG Subsampling value is incorrect. It should be one of the available SubSampling enumeration values: 111, 211, 411, or 211v.
7111	ValueOutOfRangeException	The PNG Filter value is incorrect. Please check the enumeration declaration for supported values.

Extended Error Codes

The following are error codes and strings that can be returned in the ConditionCode and ConditionDescription properties when TwainPRO returns a TWERR_TWAIN error.

1	TWCC_BUMMER	General failure. Unload Source immediately.
2	TWCC_LOWMEMORY	Not enough memory to complete operation.
3	TWCC_NODS	Source Manager unable to find the specified Source.
4	TWCC_MAXCONNECTIONS	Source is connected to maximum supported number of applications.
5	TWCC_OPERATIONERROR	Source or Source Manager reported an error to the user and handled the error; no application action required.
6	TWCC_BADCAP	Capability not supported by Source.
9	TWCC_BADPROTOCOL	Unrecognized operation triplet.
10	TWCC_BADVALUE	Data parameter out of supported range.
11	TWCC_SEQERROR	Illegal operation for current Source Manager or Source state.
12	TWCC_BADDEST	Unknown destination in DSM_Entry.
13	TWCC_CAPUNSUPPORTED	Capability not supported by Source.
14	TWCC_CAPBADOPERATION	Operation not supported on capability.
15	TWCC_CAPSEQERROR	Capability has dependencies on other capabilities and cannot be operated upon at this time.
16	TWCC_DENIED	File System operation is denied (file is protected).
17	TWCC_FILEEXISTS	Operation failed because file already exists.
18	TWCC_FILENOTFOUND	File not found.
19	TWCC_NOTEMPTY	Operation failed because directory is not empty.
20	TWCC_PAPERJAM	Transfer failed because of a feeder error.
21	TWCC_PAPERDOUBLEFEED	Transfer failed because of a feeder error.
22	TWCC_FILEWRITEERROR	Error writing the file.
23	TWCC_CHECKDEVICEONLINE	The device went off-line prior to or during this operation.
24	TWCC_INTERLOCK	Operation failed because the cover or door is open.
25	TWCC_DAMAGEDCORNER	Operation failed because the document has a damaged corner.
26	TWCC_FOCUSERROR	Operation failed because of a focusing error during document capture.
27	TWCC_DOCTOOLIGHT	Operation failed because the document is too light.
28	TWCC_DOCTOODARK	Operation failed because the document is too dark.
29	TWCC_NOMEDIA	Operation failed because no media is present for the source to capture.