@fdewaelle: Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 6.1.2

Error message:
Invalid access to memory.

Stack trace:
(00D2870F) TRemoteFile::Duplicate
(01003DEA) C6083_0
(01005E52) ____ExceptionHandler
(01002C0C) __ExceptionHandler
(00097FAF) ntdll.dll
(00076221) ntdll.dll.KiUserExceptionDispatcher
(00D2871A) TRemoteFile::Duplicate
(00D2871A) TRemoteFile::Duplicate
(00D2C826) TRemoteFileList::CloneStrings
(000185E6) TCustomScpExplorerForm::DeleteFiles
(00011F90) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012046) TCustomScpExplorerForm::ExecuteFileOperation
(0001224C) TCustomScpExplorerForm::ExecuteFileOperation
(0001240B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D89C) TNonVisualDataModule::ExplorerActionsExecute
(0026344C) System::Actions::TContainedActionList::ExecuteAction

(01004455) C6083_0
(01005A2F) _ReThrowException
(00D288D6) TRemoteFile::Duplicate
(00D2871A) TRemoteFile::Duplicate
(00D2871A) TRemoteFile::Duplicate
(00D2C826) TRemoteFileList::CloneStrings
(000185E6) TCustomScpExplorerForm::DeleteFiles
(00011F90) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012046) TCustomScpExplorerForm::ExecuteFileOperation
(0001224C) TCustomScpExplorerForm::ExecuteFileOperation
(0001240B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D89C) TNonVisualDataModule::ExplorerActionsExecute
(0026344C) System::Actions::TContainedActionList::ExecuteAction

(01004455) C6083_0
(01005A2F) _ReThrowException
(00D288D6) TRemoteFile::Duplicate
(00D2871A) TRemoteFile::Duplicate
(00D2C826) TRemoteFileList::CloneStrings
(000185E6) TCustomScpExplorerForm::DeleteFiles
(00011F90) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012046) TCustomScpExplorerForm::ExecuteFileOperation
(0001224C) TCustomScpExplorerForm::ExecuteFileOperation
(0001240B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D89C) TNonVisualDataModule::ExplorerActionsExecute
(0026344C) System::Actions::TContainedActionList::ExecuteAction

(01004455) C6083_0
(01005A2F) _ReThrowException
(00D288D6) TRemoteFile::Duplicate
(00D2C826) TRemoteFileList::CloneStrings
(000185E6) TCustomScpExplorerForm::DeleteFiles
(00011F90) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012046) TCustomScpExplorerForm::ExecuteFileOperation
(0001224C) TCustomScpExplorerForm::ExecuteFileOperation
(0001240B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D89C) TNonVisualDataModule::ExplorerActionsExecute
(0026344C) System::Actions::TContainedActionList::ExecuteAction

(01004455) C6083_0
(01005A2F) _ReThrowException
(00018ACD) TCustomScpExplorerForm::DeleteFiles
(00011F90) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012046) TCustomScpExplorerForm::ExecuteFileOperation
(0001224C) TCustomScpExplorerForm::ExecuteFileOperation
(0001240B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D89C) TNonVisualDataModule::ExplorerActionsExecute
(0026344C) System::Actions::TContainedActionList::ExecuteAction

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.

@alexandro.crz: Thanks for your report.
I have sent you an email with a debug version of WinSCP to the address you have used to register on this forum.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 6.1

Error message:
Acesso inválido à memória

Rastreamento de pilha:
(00D2954B) TRemoteFile::Duplicate
(01004C0A) C6085_3
(01006C72) ____ExceptionHandler
(01003A2C) __ExceptionHandler
(000974CF) ntdll.dll
(00077751) ntdll.dll.KiUserExceptionDispatcher
(00D29556) TRemoteFile::Duplicate
(00D2D662) TRemoteFileList::CloneStrings
(000185B6) TCustomScpExplorerForm::DeleteFiles
(00011F60) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012016) TCustomScpExplorerForm::ExecuteFileOperation
(0001221C) TCustomScpExplorerForm::ExecuteFileOperation
(000123DB) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D86C) TNonVisualDataModule::ExplorerActionsExecute
(00262B34) System::Actions::TContainedActionList::ExecuteAction

(01005275) C6085_3
(0100684F) _ReThrowException
(00D29712) TRemoteFile::Duplicate
(00D29556) TRemoteFile::Duplicate
(00D2D662) TRemoteFileList::CloneStrings
(000185B6) TCustomScpExplorerForm::DeleteFiles
(00011F60) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012016) TCustomScpExplorerForm::ExecuteFileOperation
(0001221C) TCustomScpExplorerForm::ExecuteFileOperation
(000123DB) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D86C) TNonVisualDataModule::ExplorerActionsExecute
(00262B34) System::Actions::TContainedActionList::ExecuteAction

(01005275) C6085_3
(0100684F) _ReThrowException
(00D29712) TRemoteFile::Duplicate
(00D2D662) TRemoteFileList::CloneStrings
(000185B6) TCustomScpExplorerForm::DeleteFiles
(00011F60) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012016) TCustomScpExplorerForm::ExecuteFileOperation
(0001221C) TCustomScpExplorerForm::ExecuteFileOperation
(000123DB) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D86C) TNonVisualDataModule::ExplorerActionsExecute
(00262B34) System::Actions::TContainedActionList::ExecuteAction

(01005275) C6085_3
(0100684F) _ReThrowException
(00018A9D) TCustomScpExplorerForm::DeleteFiles
(00011F60) TCustomScpExplorerForm::ExecuteDeleteFileOperation
(00012016) TCustomScpExplorerForm::ExecuteFileOperation
(0001221C) TCustomScpExplorerForm::ExecuteFileOperation
(000123DB) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0004D86C) TNonVisualDataModule::ExplorerActionsExecute
(00262B34) System::Actions::TContainedActionList::ExecuteAction

I know how to reproduce the problem or the problem happens frequently enough. I wish to be contacted by the WinSCP team to help resolving the problem.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>
I highlighted two files on a server, right-clicked and chose download. I browsed to a location on another server to which I often download and started the download. I tried again after this error (it did not remember the destination and I had to browse to it again) and it worked.
WinSCP 5.17.7

Error message:
Invalid access to memory.

Stack trace:
(00CCA457) TRemoteFile::Duplicate
(00F8862A) C5296_3
(00F8A692) ____ExceptionHandler
(00F8744C) __ExceptionHandler
(00088F2F) ntdll.dll
(000743C1) ntdll.dll.KiUserExceptionDispatcher
(00CCA462) TRemoteFile::Duplicate
(00CCE58E) TRemoteFileList::CloneStrings
(0000FCD4) TCustomScpExplorerForm::ExecuteCopyMoveFileOperation
(00010848) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00010C46) TCustomScpExplorerForm::ExecuteCopyOperationCommand
(000440FF) TNonVisualDataModule::ExplorerActionsExecute
(003E85CC) System::Actions::TContainedActionList::ExecuteAction
(001C71B5) Vcl::Actnlist::TCustomAction::Execute
(003A4BA8) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

(00F88C95) C5296_3
(00F8A26F) _ReThrowException
(00CCA603) TRemoteFile::Duplicate
(00CCA462) TRemoteFile::Duplicate
(00CCE58E) TRemoteFileList::CloneStrings
(0000FCD4) TCustomScpExplorerForm::ExecuteCopyMoveFileOperation
(00010848) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00010C46) TCustomScpExplorerForm::ExecuteCopyOperationCommand
(000440FF) TNonVisualDataModule::ExplorerActionsExecute
(003E85CC) System::Actions::TContainedActionList::ExecuteAction
(001C71B5) Vcl::Actnlist::TCustomAction::Execute
(003A4BA8) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

(00F88C95) C5296_3
(00F8A26F) _ReThrowException
(00CCA603) TRemoteFile::Duplicate
(00CCE58E) TRemoteFileList::CloneStrings
(0000FCD4) TCustomScpExplorerForm::ExecuteCopyMoveFileOperation
(00010848) TCustomScpExplorerForm::ExecuteFileOperation
(00010A39) TCustomScpExplorerForm::ExecuteFileOperation
(00010ABF) TCustomScpExplorerForm::ExecuteFileOperationCommand
(00010C46) TCustomScpExplorerForm::ExecuteCopyOperationCommand
(000440FF) TNonVisualDataModule::ExplorerActionsExecute
(003E85CC) System::Actions::TContainedActionList::ExecuteAction
(001C71B5) Vcl::Actnlist::TCustomAction::Execute
(003A4BA8) System::Classes::_18201
(000437A9) USER32.dll
(000242A7) USER32.dll
(000233F9) USER32.dll
(000231DB) USER32.dll.DispatchMessageW

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.9.4

Error message:
Chyba přístupu do paměti.

Stack trace:
(006D00BB) TRemoteFile::Duplicate
(00866B5E) C5073_0
(00868BC6) ____ExceptionHandler
(00865980) __ExceptionHandler
(000851DF) ntdll.dll
(00073161) ntdll.dll.KiUserExceptionDispatcher
(006C7883) TTransferQueueItem::TTransferQueueItem
(006C7FDF) TDownloadQueueItem::TDownloadQueueItem
(00007717) TCustomScpExplorerForm::AddQueueItem
(0000DFAA) TCustomScpExplorerForm::ExecuteFileOperation
(0000EAB8) TCustomScpExplorerForm::ExecuteFileOperation
(0000EB3F) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003763A) TNonVisualDataModule::ExplorerActionsExecute
(003B5348) System::Actions::TContainedActionList::ExecuteAction
(0019C4C1) Vcl::Actnlist::TCustomAction::Execute
(0037322C) System::Classes::_18201
(00031F89) USER32.dll
(0002443E) USER32.dll
(00023DCD) USER32.dll
(00023B9B) USER32.dll.DispatchMessageW

(008671C9) C5073_0
(008687A3) _ReThrowException
(006D0254) TRemoteFile::Duplicate
(006C7883) TTransferQueueItem::TTransferQueueItem
(006C7FDF) TDownloadQueueItem::TDownloadQueueItem
(00007717) TCustomScpExplorerForm::AddQueueItem
(0000DFAA) TCustomScpExplorerForm::ExecuteFileOperation
(0000EAB8) TCustomScpExplorerForm::ExecuteFileOperation
(0000EB3F) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003763A) TNonVisualDataModule::ExplorerActionsExecute
(003B5348) System::Actions::TContainedActionList::ExecuteAction
(0019C4C1) Vcl::Actnlist::TCustomAction::Execute
(0037322C) System::Classes::_18201
(0

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.7

Error message:
Invalid access to memory.

Stack trace:
(0067C8EF) TRemoteFile::Duplicate
(007E08AA) C4799_0
(007E2912) ____ExceptionHandler
(007DF88C) __ExceptionHandler
(00062496) ntdll.dll
(0000F13E) ntdll.dll.KiUserExceptionDispatcher
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0001B603) TCustomScpExplorerForm::RemoteFileControlFileOperation
(0001B8EA) TCustomScpExplorerForm::RemoteFileControlDDEnd
(003DA7C6) Customdirview::TCustomDirView::DDDragDetect
(00615DA6) TUnixDirView::DDDragDetect
(003D6CFC) Customdirview::TCustomDirView::CNNotify
(00217AC5) Vcl::Controls::TControl::WndProc
(0021C609) Vcl::Controls::TWinControl::WndProc
(00260537) Vcl::Comctrls::TCustomListView::WndProc
(0021C76F) Vcl::Controls::_17076
(0021C609) Vcl::Controls::TWinControl::WndProc
(0021BC50) Vcl::Controls::TWinControl::MainWndProc
(0034059C) System::Classes::_18201
(000152F7) USER32.dll
(00015D35) USER32.dll
(00015DE8) USER32.dll
(00015E49) USER32.dll
(0000F117) ntdll.dll.KiUserCallbackDispatcher
(000186D0) USER32.dll.SendMessageW
(0002B06D) COMCTL32.DLL
(000D0845) COMCTL32.DLL
(000A207A) COMCTL32.DLL
(000A10E2) COMCTL32.DLL
(0002EE7B) COMCTL32.DLL
(000152F7) USER32.dll
(00015D35) USER32.dll
(0001FD32) USER32.dll
(0001FD58) USER32.dll.Call

The problem happens rarely. I cannot reproduce it.

In a remote directory I used ctrl+a to select all files, I right clicked on the files and selected "Download and delete". After a good 10 minutes of transfer I selected "Minimize" then "Proceed in background". This is when the error occurred. I can't seem to replicate it.
<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.7

Error message:
Invalid access to memory.

Stack trace:
(0067C8EF) TRemoteFile::Duplicate
(007E08AA) C4799_0
(007E2912) ____ExceptionHandler
(007DF88C) __ExceptionHandler
(00045A86) ntdll.dll
(0000F13E) ntdll.dll.KiUserExceptionDispatcher
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003229E) TNonVisualDataModule::ExplorerActionsExecute
(00382614) System::Actions::TContainedActionList::ExecuteAction
(0016A155) Vcl::Actnlist::TCustomAction::Execute
(0034059C) System::Classes::_18201
(000152F7) USER32.dll
(00015D35) USER32.dll
(000167BF) USER32.dll
(00016885) USER32.dll.DispatchMessageW

(007E0F15) C4799_0
(007E24EF) _ReThrowException
(0067CA88) TRemoteFile::Duplicate
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003229E) TNonVisualDataModule::ExplorerActionsExecute
(00382614) System::Actions::TContainedActionList::ExecuteAction
(0016A155) Vcl::Actnlist::TCustomAction::Execute
(0034059C) System::Classes::_18201
(000152F7) USE

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.7

Error message:
Invalid access to memory.

Stack trace:
(0067C8EF) TRemoteFile::Duplicate
(007E08AA) C4799_0
(007E2912) ____ExceptionHandler
(007DF88C) __ExceptionHandler
(0005A5DA) ntdll.dll
(0000F12E) ntdll.dll.KiUserExceptionDispatcher
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003229E) TNonVisualDataModule::ExplorerActionsExecute
(00382614) System::Actions::TContainedActionList::ExecuteAction
(0016A155) Vcl::Actnlist::TCustomAction::Execute
(0034059C) System::Classes::_18201
(000152F7) USER32.dll
(00015D35) USER32.dll
(000167BF) USER32.dll
(00016885) USER32.dll.DispatchMessageW

(007E0F15) C4799_0
(007E24EF) _ReThrowException
(0067CA88) TRemoteFile::Duplicate
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003229E) TNonVisualDataModule::ExplorerActionsExecute
(00382614) System::Actions::TContainedActionList::ExecuteAction
(0016A155) Vcl::Actnlist::TCustomAction::Execute
(0034059C) System::Classes::_18201
(000152F7) USE

The problem happens rarely. I cannot reproduce it.

I selected 2500 files (one file is 750KB)and pressing F6 (copy and remove)
When files is downloading, in transfer window I pressing button minimize.
Then application abortin with this message.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.7

Error message:
Naruszenie ochrony pamęci.

Stack trace:
(0067C8EF) TRemoteFile::Duplicate
(007E08AA) C4799_0
(007E2912) ____ExceptionHandler
(007DF88C) __ExceptionHandler
(0008A61F) ntdll.dll
(00077E7A) ntdll.dll.KiUserExceptionDispatcher
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003212D) TNonVisualDataModule::ExplorerActionsExecute
(00382614) System::Actions::TContainedActionList::ExecuteAction
(0016A155) Vcl::Actnlist::TCustomAction::Execute

(007E0F15) C4799_0
(007E24EF) _ReThrowException
(0067CA88) TRemoteFile::Duplicate
(0067438B) TTransferQueueItem::TTransferQueueItem
(00674AE7) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003212D) TNonVisualDataModule::ExplorerActionsExecute
(00382614) System::Actions::TContainedActionList::ExecuteAction
(0016A155) Vcl::Actnlist::TCustomAction::Execute

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.8.1

Error message:
Invalid access to memory.

Stack trace:
(006A166F) TRemoteFile::Duplicate
(008300A2) C5066_0
(0083210A) ____ExceptionHandler
(0082F084) __ExceptionHandler
(0008A63F) ntdll.dll
(00077E9A) ntdll.dll.KiUserExceptionDispatcher
(00698E13) TTransferQueueItem::TTransferQueueItem
(0069956F) TDownloadQueueItem::TDownloadQueueItem
(000071F3) TCustomScpExplorerForm::AddQueueItem
(0000C670) TCustomScpExplorerForm::ExecuteFileOperation
(0000D0F4) TCustomScpExplorerForm::ExecuteFileOperation
(0000D17B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003407B) TNonVisualDataModule::ExplorerActionsExecute
(00394634) System::Actions::TContainedActionList::ExecuteAction
(0017B859) Vcl::Actnlist::TCustomAction::Execute
(0035257C) System::Classes::_18201
(000374F1) USER32.dll
(00015C3B) USER32.dll
(0001553C) USER32.dll
(000152FB) USER32.dll.DispatchMessageW

(0083070D) C5066_0
(00831CE7) _ReThrowException
(006A1808) TRemoteFile::Duplicate
(00698E13) TTransferQueueItem::TTransferQueueItem
(0069956F) TDownloadQueueItem::TDownloadQueueItem
(000071F3) TCustomScpExplorerForm::AddQueueItem
(0000C670) TCustomScpExplorerForm::ExecuteFileOperation
(0000D0F4) TCustomScpExplorerForm::ExecuteFileOperation
(0000D17B) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003407B) TNonVisualDataModule::ExplorerActionsExecute
(00394634) System::Actions::TContainedActionList::ExecuteAction
(0017B859) Vcl::Actnlist::TCustomAction::Execute
(0035257C) System::Classes::_18201
(000374F1) US

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.6

Error message:
Invalid access to memory.

Stack trace:
(0067BD9F) TRemoteFile::Duplicate
(007E46BA) C4799_3
(007E6722) ____ExceptionHandler
(007E369C) __ExceptionHandler
(0005A5DA) ntdll.dll
(0000F12E) ntdll.dll.KiUserExceptionDispatcher
(0067383B) TTransferQueueItem::TTransferQueueItem
(00673F97) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003212D) TNonVisualDataModule::ExplorerActionsExecute
(00382320) System::Actions::TContainedActionList::ExecuteAction
(00169E61) Vcl::Actnlist::TCustomAction::Execute

(007E4D25) C4799_3
(007E62FF) _ReThrowException
(0067BF38) TRemoteFile::Duplicate
(0067383B) TTransferQueueItem::TTransferQueueItem
(00673F97) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003212D) TNonVisualDataModule::ExplorerActionsExecute
(00382320) System::Actions::TContainedActionList::ExecuteAction
(00169E61) Vcl::Actnlist::TCustomAction::Execute

The problem happens rarely. I cannot reproduce it.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.7.6

Error message:
Invalid access to memory.

Stack trace:
(0067BD9F) TRemoteFile::Duplicate
(007E46BA) C4799_3
(007E6722) ____ExceptionHandler
(007E369C) __ExceptionHandler
(0005A5DA) ntdll.dll
(0000F12E) ntdll.dll.KiUserExceptionDispatcher
(0067383B) TTransferQueueItem::TTransferQueueItem
(00673F97) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003212D) TNonVisualDataModule::ExplorerActionsExecute
(00382320) System::Actions::TContainedActionList::ExecuteAction
(00169E61) Vcl::Actnlist::TCustomAction::Execute

(007E4D25) C4799_3
(007E62FF) _ReThrowException
(0067BF38) TRemoteFile::Duplicate
(0067383B) TTransferQueueItem::TTransferQueueItem
(00673F97) TDownloadQueueItem::TDownloadQueueItem
(0000715B) TCustomScpExplorerForm::AddQueueItem
(0000C57D) TCustomScpExplorerForm::ExecuteFileOperation
(0000CFB0) TCustomScpExplorerForm::ExecuteFileOperation
(0000D037) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0003212D) TNonVisualDataModule::ExplorerActionsExecute
(00382320) System::Actions::TContainedActionList::ExecuteAction
(00169E61) Vcl::Actnlist::TCustomAction::Execute

The problem happens rarely. I cannot reproduce it.