A .pptx deck looks like one file, but it is a ZIP package of many parts: a part for each slide, for each slide layout and master, for each picture and chart, and lists that tell PowerPoint what each part is and how the parts are linked. If a save was interrupted, a download was cut short, or a few bytes changed, one part or one link may be wrong, and PowerPoint says that it found a problem with the content, even though most of the slides are still in the file.
Add the deck on this page. It reads whatever can be read, repairs the XML in the slides, fixes the links between the parts, and writes a clean copy. It tells you what was wrong, what it did, and what it could not keep, and it lists the text of every slide, so that you can copy it out even if the repaired deck is not perfect. Nothing is uploaded, and the code behind the page makes no network requests, which matters for a deck that you are not meant to share.
How to use the Repair PPTX: Fix a Corrupted PowerPoint File in Your Browser
- Add the deckDrop the PowerPoint file that will not open on the box, or choose it from your device. It is read on your device and does not leave it. Files up to 150 MB are accepted, in the .pptx, .pptm, .potx, and .ppsx formats.
- Read what the page foundThe page says in one line whether the file was fine, repaired, or repaired with some loss. Below that it lists what was wrong, what was done, and what could not be kept, each with the part of the file it concerns, such as ppt/slides/slide4.xml.
- Check the slidesThe number of slides, words, pictures, and tables is shown, with the text of each slide in order. If you only need the words, download them as a .txt file.
- Download the repaired deckDownload the repaired .pptx, open it in PowerPoint, and compare it with the text. The page cannot test the file in PowerPoint itself, so treat the first opening as the real check, and keep your original.
What is inside a .pptx file
The Library of Congress describes a PPTX file as marked up in PresentationML and DrawingML, and packaged with the Open Packaging Conventions, which are based on ZIP. Rename the file to .zip and you can open it. The top level of the package has the folders _rels, docProps, and ppt, and one file, [Content_Types].xml. The ppt folder holds presentation.xml, one part for each slide, the slide layouts and masters that the slides use, the pictures in a media folder, and charts.
The presentation part lists the slides in order, each by a link ID, and the relationship files turn each ID into a part name. A slide does not hold its own design. It has a link to a slide layout, which has a link to a slide master. If the layout is missing, PowerPoint cannot open the slide. If a picture is missing, the slide shows a gap or the file is refused. When any list is missing or points to nothing, PowerPoint reports a problem with the content, even if every slide is intact.
How a deck gets damaged
The most common cause is a file that ends too soon: an interrupted download, an email attachment that was cut, a sync program that stopped halfway, a crash in the middle of a save. A ZIP file keeps its list of parts at the end, as the PKWARE format description explains, so a cut loses the list while the parts before the cut are still there. This page does not need the list. It finds each part by its header.
Other causes are changed bytes, which break the checksum of a compressed part, and programs that write a file badly. A cut in the middle of a slide leaves a text box with no paragraph and a shape without its properties, which PowerPoint does not accept. A cut early in the file may take the presentation part, and with it the order of the slides. The page writes it again from the slides that are left.
How the file is read
Every part of a ZIP file is compressed with the DEFLATE method, described in RFC 1951. The browser's own decompressor throws away the output of a stream that turns out to be damaged. This page has its own decoder, which keeps everything it decoded up to the point of the damage and says where it stopped. A slide that was cut off in the middle is therefore not lost: its first text boxes are used.
Each part is checked against the size and checksum that the file recorded. A part that matches is in order. A part that decodes but does not match is marked as changed. A part that stops early is marked as cut off. Where compressed data is damaged, the last paragraph before the point where decoding stopped is dropped, because the bytes just before the damage are often wrong.
What is repaired
XML parts are read by a tolerant reader and written again as strict XML. It closes elements that were left open at a cut, removes end tags that close nothing, repairs an end tag whose name was damaged by a character or two, escapes ampersands that are not part of an entity, removes characters that XML does not allow, and declares again the namespace prefixes that a damaged part lost.
PowerPoint has its own rules on top of XML. A slide needs a shape tree, a text box needs at least one paragraph, and a shape needs its properties. A cut leaves these out, so the page adds the empty ones, and it removes a shape that was cut off before the parts that identify it. A link to a picture, chart, or other part that is not in the file is removed, with the picture or shape that used it, and the rest of the slide stays. A slide whose layout is missing is removed, with its link, and the page names it.
When the presentation part cannot be repaired
If the presentation part cannot be read as XML, or the list of its links is gone, the page writes both again from the slides and masters it found. The slides are put in the order of their file names, which is the order in which PowerPoint creates them but not necessarily the order you arranged them in. The slide size is set to widescreen, 16:9, because the original size is in the part that was lost, so check both in PowerPoint under Design and Slide Size. If no slide or no master can be read, the page says that nothing could be recovered.
A file that is not a .pptx is told apart and not guessed at. A Word or Excel file, an older .ppt file, a password-protected file, and a PDF each get their own message. The older .ppt format is not a ZIP package, and this page does not repair it. In PowerPoint, try File, Open, choose the file, press the arrow next to Open, and choose Open and Repair.
How the repair was tested
A deck was made with python-pptx, which is not part of this page. It has six slides: a title slide with notes, three slides with bullet text that includes special characters, a slide with a table and a picture, and a slide with a chart. It was tried undamaged and then damaged in 21 ways: cut inside two slides at two points each, with the list of parts removed, with the ending cut off, with a slide layout, a slide, the pictures, or the chart removed, with the presentation part wrecked or its links missing, with the list of content types or package relationships missing, with four kinds of XML damage in a slide, and with single bytes flipped in compressed data.
The 21 repaired decks were opened with python-pptx, tested with Python's zipfile, and parsed with lxml's strict XML reader. All passed. The text of each slide that python-pptx reads was the real text of the original, and the number of slides and the text that the page listed matched what python-pptx read. The exceptions are the cases where bytes were flipped, in which the text of the damaged slide is different. A last test damaged the workbook and deck samples in random ways, 60 times, and every file was either repaired and passed its own checks, or refused with a clear message.
Limits and accuracy
- The repaired deck was not opened in Microsoft PowerPoint, because PowerPoint was not available for the tests. It was read by python-pptx, lxml, and zipfile. Open it in PowerPoint, and keep your original.
- The older .ppt format is not supported. It is a different kind of file, and this page repairs .pptx decks, which are ZIP packages. Files protected with a password are not repaired either.
- Where compressed data is damaged in the middle, the content after the damage is lost, and the text just before it may be wrong. A checksum that does not match is reported, but the page cannot tell which words are wrong.
- A slide whose layout is gone is removed. A picture, chart, or shape whose part is gone is removed, and the page does not try to guess what it showed.
- When the presentation part is written again, the order of the slides is the order of their file names, and the size is widescreen. Sections, custom shows, and slide timings are not in it.
- The page checks the package, the XML, the links, and the rules for slides that are listed above. It does not check animations, transitions, or every rule of the presentation schema, so a file that is sound by these checks may still be refused by PowerPoint.
- The text of a slide is listed in the order of its shapes in the file, which may differ from the reading order on the slide. Text inside pictures and charts is not read.
- A macro-enabled file (.pptm) is repaired as a package, and its macros are kept as they are. The page does not run or check them.
Frequently asked questions
How do I repair a corrupted PPTX file?
Add the deck on this page. It reads the parts of the package, repairs the XML in the slides and the links between the parts, and writes a clean copy that you download. It lists what was wrong and what could not be kept, and it shows the text of every slide.
Why does PowerPoint say that it found a problem with the content?
PowerPoint refuses the file if one list is missing, one link points to nothing, a slide has no layout, a text box has no paragraph, or a part is not well-formed XML, even when most slides are intact. Fixing the structure often brings the deck back.
Can it recover a deck that was cut off during a download or a save?
Often, yes. The ZIP list of parts is at the end of the file, so a cut loses it, but the parts before the cut can still be read. The slides before the cut are kept, and a slide cut in the middle gives its text up to the cut.
Will the pictures, notes, and formatting be kept?
Those in the parts that were recovered stay, including the layouts and masters that the slides use. A picture or chart whose part is missing is removed from its slide. Speaker notes stay if their parts are in the file.
Does it work on .ppt files?
No. A .ppt file is the older binary format, not a ZIP package. This page repairs .pptx decks. For a .ppt file, try PowerPoint's Open and Repair command: choose File, Open, select the file, press the arrow next to Open, and choose Open and Repair.
Can I get the text if the repair is not perfect?
Yes. The page lists the text of every slide it could read, even when a repaired deck is not offered, and you can download it as a .txt file. If no text can be found in any slide, the page says that nothing could be recovered.
Is my deck uploaded to a server?
No. The file is read and repaired in your browser, and the code behind the page makes no network requests. The repaired copy and the text are created on your device and downloaded from there.
Research and references
This page was written and checked against the sources below.
