mean the file is damaged. For example, it may have been corrupted when it was copied or not have downloaded fully from a remote location. The original file could also be corrupted or damaged for other reasons, for example Mozilla Firefox can cause this in cases where the PDF file is larger than its cache limit.
Please note that PDF-XChange Viewer is designed to open and edit PDF files. Although PDF-XChange Viewer can create PDF files from alternative formats, it does not contain the functionality to open those formats. Additionally, it should be noted that PDF-XChange Editor has superseded PDF-XChange Viewer, which has been discontinued. PDF-XChange Editor contains the functionality to open a wide range of file formats, and upgrading to this application should resolve the issue. It is available here.
The first option in the case of damaged files is to attempt to copy/download them again in order to ensure that the issue was not a procedural error.
If PDF-XChange Viewer is opening a file within Mozilla Firefox and one of the above error messages are returned then it is possible that the file exceeds the cache limit. There are several methods that can be used to resolve this issue:
All versions of PDF-XChange Viewer from build 52 and all versions of PDF-XChange Editor include the option to download files as streams, rather than use the Firefox cache method to download files. This will resolve the issue, but please note that viewing very large files may affect performance.
The latest version of PDF-XChange Viewer is availablehere.