"There is no application set to open the document" on a Mac

The message “There is no application set to open the document” means macOS does not know which app should handle that type of file. It is a statement about the file’s type, not its health: the file may be perfectly fine. You have three ways forward: pick an app for it yourself, correct a missing or wrong extension, or convert the file into a format the Mac already opens.

What the message means

When you double-click a file, macOS reads its extension, looks up which app is registered for that type, and hands the file over. When no app on the Mac claims the type, you get this message with three buttons: Choose Application, Search App Store and Cancel.

There are four usual reasons.

• The format has no built-in app. Windows-era video such as WMV and AVI, MKV video, WMA and OGG audio, and files from specialist software all fall here.
• The extension is missing or wrong. A file called report with nothing after it, a download that still ends in .part, or a generic .dat gives macOS nothing to go on.
• The app that used to open it is gone. Remove an app, and the files only it could open are left without an owner.
• It is not a document at all. Windows programs (.exe, .msi) and the internal data files of other apps were never meant to be opened by double-clicking on a Mac.

Step 1: find out what the file really is

1. Select the file and press Command-I. Read the Kind line, then open Name and Extension to see the full name. Finder hides some extensions; to show them all, choose Finder, Settings, Advanced, and tick Show all filename extensions.
2. Check the size in the same window. A file of zero bytes, or a few kilobytes when you expected a video, has nothing in it to open. Download or copy it again.
3. Ask the Mac to look inside. Open Terminal, type file followed by a space, drag the file into the window and press Return.

The file command ignores the name and reads the contents. Typical answers are “PDF document”, “Zip archive data”, “ISO Media” for the MP4 and MOV family, “Matroska data” for MKV, “Microsoft ASF” for WMV and WMA, “HTML document” and “ASCII text”. If it says only “data”, the Mac does not recognize the contents either.

If the answer shows the file is an ordinary type with the wrong name, fix the name. A file with no extension that will not open walks through adding the right one, and a downloaded file that stays a .part or .download covers unfinished downloads.

Step 2: try an app you already have

1. Right-click the file and choose Open With. If a suitable app is listed, choose it.
2. If not, choose Other. In the window that opens, change Enable from Recommended Applications to All Applications, and select the app you want to try.
3. Tick Always Open With if you want this one file to keep using that app.

Sensible first guesses: TextEdit for anything file describes as text, Preview for images and PDFs, QuickTime Player for video and audio.

To set the app for every file of that type, select one such file, press Command-I, pick the app under Open with, and click Change All.

Trying the wrong app does no harm. You will see an error or a page of symbols. Close it without saving, because saving from the wrong app can overwrite a good file with nonsense.

Step 3: when nothing on the Mac opens it

You have two choices. Install an app that reads the format (the Search App Store button in the message looks for one), or convert the file into something the Mac already handles.

Converting is often the better choice for a file you only need to read, watch or pass on, and it leaves you with something every other device can open as well. Manatee accepts 122 input types and converts them on the Mac:

• WMV, MKV, AVI, FLV, WebM and other video to MP4 or MOV.
• WMA, OGG, Opus, APE and other audio to MP3, M4A, WAV or FLAC.
• Uncommon images such as JPEG XL, TGA, EXR and camera raw to JPEG, PNG, HEIC or TIFF.
• Older documents such as .doc, WordML and webarchive to DOCX, RTF or TXT.

Open Manatee, choose Convert, drop the file in and pick the target. You can also right-click the file in Finder and choose Services, Fix with Manatee. The result is a new copy beside the original, which is never modified. Nothing is uploaded and there is no account. It is free for 24 hours with every feature, then $9 once.

What it will not do: it does not run Windows programs, it does not convert Pages, Numbers or Keynote files, and it does not unlock protected files. RAR and 7z archives are not among its inputs either; for those, see RAR, 7z and tar.gz archives on a Mac.

When the file opens but looks wrong

If you chose the right kind of app, or converted the file, and still get an error, a blank window or a video that stops early, the type was never the whole problem. The file is probably incomplete or damaged.

• Compare its size with what the sender or the website says it should be.
• Download it again, or ask for it to be sent another way. A fresh copy is always better than a repair.
• If this is the only copy, Manatee’s Repair mode works on damaged video, PDF and Word documents. It reports Fixed, Partial (it says how much came back) or Not fixable. Data that is gone is gone, and it says so plainly.

Questions

Does this message mean the file is corrupted? No. It means no app is assigned to that type. A damaged file with a normal extension produces a different error, from the app that tried to open it.

Why did this start after I deleted an app? That app was the registered owner of the file type. Reinstall it, or use Get Info and Change All to hand the type to another app that can read it.

Can I change the extension to make the file open? Only when the extension was wrong to begin with. Renaming a .wmv to .mp4 does not convert anything: the contents are the same, and the app that now tries to open it will fail.

Is it safe to open a file of an unknown type? Viewing a document, picture or video carries little risk. Be careful with anything that is a program, installer or script, particularly from a sender you do not know. Running file on it first tells you which you are dealing with.