1 correct answer adorobat • adobe employee, hi ajflynn, sorry for the delay in response. pdf showing invalid format pc shastra 52. mutool ( project page, manpage ) will repair broken pdfs without printing them. as per the screenshot, it seems the file you are trying to open is not a valid pdf file. are you experiencing this issue in downloading other pdf as well? pages in the end of the filename). 1k views 1 year ago change pdf icons back to default adobe reader/ acrobat: stop pdf files opening in invalid format. are you downloading file on desktop or mobile device? 7k subscribers subscribe 5. regards, meenakshi upvote translate hi stuart taylor, please let us know the dot version of adobe application and os you are using? pdf] [ pages] the clean command pretty prints and rewrites the syntax of a pdf file. if any updates are available, pdf invalid format install them and then try re- opening your pdf on the app. could you please also share the source from where you are trying to download file. on ubuntu: sudo apt- get install mupdf- tools. launch adobe acrobat reader and go to help > check for updates. in which case, go to help > repair installation. the issue may simply be that your adobe acrobat reader software is not up to date. also, it seems you are not using adobe application - adobe reader or adobe acrobat to open pdf files. mutool clean [ options] input. run it like this: mutool clean input. the files adobe requires to run may have become corrupted.