You double click a PDF thumbnail and open it as usual, you assume the file can be opened and viewed, but it cannot and there come out error messages such as “Format error: Not a PDF or corrupted”, “Failed to load PDF document”, it means your PDF file is corrupt.
PDF corruption can strike at any time, it may be caused by bad sector, malware attack, improper saving or transferring, incorrect storage device unplug, computer crash, system bug and so on. Whatever the reason is, we are here to share 10 ways to repair and open corrupt PDF in this article, including online free solutions.
Best Data Recovery for Windows and Mac
Free Download Windows 11/10/8/7
Free Download macOS 10.9 or later If your need to repair a PDF urgently, the easiest way is to enlist a professional PDF repair tool to rescue your damaged files.
Cisdem Data Recovery is one of the most popular data recovery tools around and it is easy to know why. It offers a comprehensive range of recovery options as well as a full support of 2000+ storage devices and 1000+ file formats. Also, it has a powerful repair tool to fix corrupted PDF, Word, Excel, PowerPoint, video and photo files.
You can opt to recover and repair files from PC/Mac disk, external storage device, even from NAS. Crashed PC Recovery mode is also allowed when your computer fails to boot. After the scan, you can select all files for recovery or repair, also you can filter and preview specific files before deciding on recovery. All the recovery and repair process run very fast but give you a delighted recovery result.
Main Features of Cisdem Data Recovery
Free Download Windows 11/10/8/7 Free Download macOS 10.9 or later 
If you want to take your chance to repair a corrupted PDF using web-based free approaches, there are 3 tools recommended: iLovePDF, PDF2GO and AvePDF. We’ve tested these tools, you can read on to find which one is the best to repair a corrupted PDF online free.
But before using these online free PDF repair tools, you should know following:
iLovePDF is an efficient tool to manipulate PDF online and free, it has a lot of straightforward tools to cope with PDF files, but it is not a PDF editor with fullest extent of editing features. Also you can upload a corrupted PDF to fix, but the chances of repairing a corrupted PDF using this tool is unknown (in my case, it is low, it didn’t repair any one of my 5 files).
The whole repair process is safe and easy, seems to be reliable, but it is still a matter of luck to repair a damaged PDF. If you want to try with this tool, just follow these steps:
It is a free service but with added features for those who subscribe, you can access to more than 20 tools that displayed in rows and columns on this website. You can find all the tools that can be found on ilovepdf, but regarding PDF repair on PDF2GO, it is more simplified, users just need to drop a corrupted file and click Start to repair.
However, it has the same problem as using ilovepdf, it is less likely to repair a PDF successfully, even retry the repair. Anyway, case by case, you can still drop your files to repair as following:
Split into five main categories, AvePDF has more than 40 tools that users can interact with and handle PDF efficiently. Due to solid features and straightforward use of the app, it becomes a great PDF solution for many. Also, it can repair PDFs, but the max upload file size is 128MB which I don’t think would be a problem.
The repair process is fast, but same as other online PDF repair tool, it is much probably can’t repair your PDF file. Anyway, since your file is corrupted and this tool just stores your file for 30 minutes, it is still worth a try.
Also, there are common and quick ways to fix a damaged PDF without installing software or uploading to 3rd server. Actually, if your PDFs corrupt often, it may be not the problem of the file itself, it may be error relating to the PDF reader, storage disk, even operating system of your machine, you can check there fixes and troubleshoot the problem one by one.
We cannot open a PDF file without a PDF reader. Sometimes, a "corrupted PDF" may be just for the reason that your PDF Reader doesn’t function properly, and chances are you have a software issue to sort, or you just need to open the PDF file in other PDF readers. There is a lot of free PDF readers, including Adobe Acrobat, PDFMaster, Preview, Google Chrome, Microsoft Edge.
Or the software issue is caused by outdated version of a PDF app, you should check for update and open the PDF in the latest version. Here we use Adobe Acrobat Reader as the example.
Many programs build in the feature to repair an installation inside the app, but you can still uninstall and reinstall the program manually to fix a corrupted PDF, a re-installation will remove all the conflicts that cause the corruption and reset all the settings back to default.
If you are using Adobe Acrobat, it allows you repair the installation as follows:
PDF corruption is often unpredictable, but bad sector on your disk is one of the main reasons leading to this, which also brings higher risk of data corruption in other file format. You are recommended to repair the disk on your Mac or Windows using the native repair tools.
Repair disk on Mac
Repair disk on Windows
A PDF cannot be opened just because some of its contents is corrupted, with an extraction by converting the corrupt PDF to other format, you may be able to re-open the file. You are recommended to convert a PDF to Word format, so that you can keep the formatting as much as possible. There are many ways to convert PDF to Word, if you want to convert with high quality, Cisdem PDF Converter OCR is a solid option, but if you want to convert for free, you can try smallpdf.
If all above listed fixes fail to repair and open the damaged PDF, maybe it’s wise to just restore a previous version, to avoid losing all the data in a PDF file. But this only applies when you have a backup of the corrupt PDF. In the case that you have backed up files on your device via backup and restore utilities, here are the steps for you to restore damaged PDFs on Windows or Mac.
It is not always a reliable option to repair PDF online, because online PDF repair tool sometime doesn’t work at all. If you have some important PDFs and want to repair badly, Cisdem Data Recovery is the best solution to both non-techies that performs basic recovery and advanced users that dig deeper under complicated data loss scenarios. The largest benefit is that Cisdem has a powerful tool to repair documents, videos and photos.
Connie has been writing for Mac productivity and utility apps since 2009. Each review and solution is based on her practical tests, she is aways energetic and trustworthy in this field.
Alice Butterworth
online pdf repair tool didn't work, don't buy it. It seems to me that the repair is just a matter of luck, don't spend too much money on it. If you have a backup, revert to previous version would be smart.