使用Inno Download Plugin下载失败时如何跳过错误继续安装

在Windows 7等部分系统上使用Inno Download Plugin下载文件时，会遇到Download failed: An error occurred in the secure channel support报错。添加idpSetOption('AllowContinue', '1');配置后未生效，需要实现非核心文件下载失败时跳过下载步骤，继续正常执行安装流程。

最小可复现示例 #

#include "D:\idp.iss"

[Setup]
PrivilegesRequired=admin
AppName=My Project
AppVersion=2.0
DefaultDirName={pf}\My Project
DefaultGroupName=My Project
UninstallDisplayIcon={app}\My Project.exe
Compression=lzma2
SolidCompression=yes
OutputDir=D:\setup
DisableDirPage=yes
DisableProgramGroupPage=yes
DisableReadyMemo=yes
DisableReadyPage=yes
OutputBaseFilename=Setup

[Files]
Source: "My Project.exe"; DestDir: "{app}"; Flags: ignoreversion

Source: "{tmp}\online.exe"; DestDir: "{commondesktop}"; Flags: external; ExternalSize: 1736547
Source: "{tmp}\offline.exe"; DestDir: "{commondesktop}"; Flags: external; ExternalSize: 166148

[Icons]
Name: "{group}\My Project"; Filename: "{app}\My Project.exe"; WorkingDir: "{app}"; Comment: "Launch My Project"

[Run]
Filename: "{app}\My Project.EXE"; Description: "My Project"; Flags: postinstall

[Code]
procedure InitializeWizard();
begin
    idpSetOption('AllowContinue', '1');
    idpAddFileSize('https://download.mysite.com/download/online.exe', ExpandConstant('{tmp}\online.exe'), 1736547);
    idpAddFileSize('https://download.mysite.com/download/offline.exe', ExpandConstant('{tmp}\offline.exe'), 166148);

    idpDownloadAfter(wpReady);
end;

需要修改两处配置即可实现下载失败自动跳过：

1. 给[Files]段中的非核心外部文件添加onlyifexists标记，确保下载失败、文件不存在时，安装流程不会因为找不到源文件终止

[Files]
Source: "My Project.exe"; DestDir: "{app}"; Flags: ignoreversion
; 新增onlyifexists标记，文件不存在时直接跳过部署
Source: "{tmp}\online.exe"; DestDir: "{commondesktop}"; Flags: external ignoreversion onlyifexists; ExternalSize: 1736547
Source: "{tmp}\offline.exe"; DestDir: "{commondesktop}"; Flags: external ignoreversion onlyifexists; ExternalSize: 166148

2. 在[Code]段添加IDP下载错误回调函数，覆盖默认的错误终止逻辑

[Code]
// 下载错误回调函数，返回True即表示忽略当前错误，继续后续流程
function idpOnError(Error: Integer; const FileName, Url: string): Boolean;
begin
  Result := True;
end;

procedure InitializeWizard();
begin
    idpSetOption('AllowContinue', '1');
    // 绑定自定义错误回调
    idpSetEvent('OnError', @idpOnError);
    idpAddFileSize('https://download.mysite.com/download/online.exe', ExpandConstant('{tmp}\online.exe'), 1736547);
    idpAddFileSize('https://download.mysite.com/download/offline.exe', ExpandConstant('{tmp}\offline.exe'), 166148);

    idpDownloadAfter(wpReady);
end;

修改完成后，任意文件下载失败都会自动跳过，不会弹出报错提示，安装流程会正常执行到结束。

内容的提问来源于stack exchange，提问作者Ramesh Patel