ZipFile.Open Method (String, ZipArchiveMode)

.NET Framework (current version)

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Opens a zip archive at the specified path and in the specified mode.

Namespace:   System.IO.Compression
Assembly:  System.IO.Compression.FileSystem (in System.IO.Compression.FileSystem.dll)

public static ZipArchive Open(
	string archiveFileName,
	ZipArchiveMode mode


Type: System.String

The path to the archive to open, specified as a relative or absolute path. A relative path is interpreted as relative to the current working directory.

Type: System.IO.Compression.ZipArchiveMode

One of the enumeration values that specifies the actions which are allowed on the entries in the opened archive.

Return Value

Type: System.IO.Compression.ZipArchive

The opened zip archive.

Exception Condition

archiveFileName is Empty, contains only white space, or contains at least one invalid character.


archiveFileName is null.


In archiveFileName, the specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must not exceed 248 characters, and file names must not exceed 260 characters.


archiveFileName is invalid or does not exist (for example, it is on an unmapped drive).


archiveFileName could not be opened.


mode is set to Create, but the file specified in archiveFileName already exists.


archiveFileName specifies a directory.


The caller does not have the required permission to access the file specified in archiveFileName.


mode specifies an invalid value.


mode is set to Read, but the file specified in archiveFileName is not found.


archiveFileName contains an invalid format.


archiveFileName could not be interpreted as a zip archive.


mode is Update, but an entry is missing or corrupt and cannot be read.


mode is Update, but an entry is too large to fit into memory.

When you set the mode parameter to Read, the archive is opened with Open from the FileMode enumeration as the file mode value. If the archive does not exist, a FileNotFoundException exception is thrown. Setting the mode parameter to Read is equivalent to calling the OpenRead method.

When you set the mode parameter to Create, the archive is opened with FileMode.CreateNew as the file mode value. If the archive already exists, an IOException is thrown.

When you set the mode parameter to Update, the archive is opened with FileMode.OpenOrCreate as the file mode value. If the archive exists, it is opened. The existing entries can be modified and new entries can be created. If the archive does not exist, a new archive is created; however, creating a zip archive in Update mode is not as efficient as creating it in Create mode.

The following example shows how to open a zip archive in the update mode and add an entry to the archive.

using System;
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication
    class Program
        static void Main(string[] args)
            string zipPath = @"c:\users\exampleuser\";
            string extractPath = @"c:\users\exampleuser\extract";
            string newFile = @"c:\users\exampleuser\NewFile.txt";

            using (ZipArchive archive = ZipFile.Open(zipPath, ZipArchiveMode.Update))
                archive.CreateEntryFromFile(newFile, "NewEntry.txt");

Universal Windows Platform
Available since 10
.NET Framework
Available since 4.5
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