Edit the extension-map file in a text editor.
Change FTP mappings in Dreamweaver
Read this article to know how to change FTP mappings in Dreamweaver.
The FTPExtensionMap.txt file (Windows) and the FTPExtensionMapMac.txt file (mac OS) map filename extensions to FTP transfer modes in ASCII or BINARY.
Each line in each of the two files includes a filename extension (such as GIF) and either the word ASCII or the word BINARY, to indicate which of the two FTP transfer modes should be used when transferring a file with that extension. In the macOS, each line also includes a creator code (such as DmWr) and a file type (such as TEXT). When you download a file with the given filename extension in macOS, Dreamweaver assigns the specified creator and file type to the file.
If a file that you are transferring does not have a filename extension, Dreamweaver uses the BINARY transfer mode.
Dreamweaver cannot transfer files in Macbinary mode. If you need to transfer files in Macbinary mode, you must use another FTP client.
The following example shows a line (from the Macintosh file) that indicates that files with the extension .html should be transferred in ASCII mode:
HTML DmWr TEXT ASCII
In both the FTPExtensionMap.txt file and FTPExtensionMapMac.txt file (macOS), all the elements on a given line are separated by tabs. The extension and the transfer mode are in uppercase letters.
To change a default setting, edit the file in a text editor.
Add information about a new filename extension
On a blank line, enter the filename extension (in uppercase letters) and press Tab.
In macOS, add the creator code, a tab, the file type, and another tab.
Enter ASCII or BINARY to set an FTP transfer mode.
Save the file.