for examle: go to http://www.threeriversparks.org/parks/elm-creek-pa
I tried that link (on linux) and it invited me to download the pdf or view it in my pdf viewer (as a separate program because by choice I don't have a pdf viewer plugin)
The fact that it's an aspx web page is irrelevant to your problem - unless you mean that you can't view the page at all.
I don't know Macs, put I think you either need a separate pdf viewer program or a pdf plugin in Firefox. Adobe Reader will of course do both.
I wonder if the original poster meant ".aspx" rather than ".ashx" because I cannot view these .aspx files in Firefox no matter how I try to open them once downloaded. I tried his/her link with the same result, a downloaded .aspx file. Also, my Preview program which reads pdf files will not open .aspx files either. Only when I change the extension on the filename to ".pdf" will it open with my reader. Like the original poster, I have no problem viewing any of these files in Safari. I wouldn't think that Firefox would need an odd work-around like changing the downloaded file's extension to ".pdf" in order to see it in another program, like my Preview.
Okay, I had this problem and finally figured out what to do. Open the Finder window and in the User location choose Downloads. Once the icons pop up, look for the files with the .aspx extension. Right-click one of them. Click on Open with, then click Other. Scroll through until you see Adobe Reader, and click it. Most importantly, check the little box at the bottom of the window that says "Always open with". Click the Open button, and it will open in Adobe Reader. I did this with about 5 files, and then it started listing Adobe Reader in the "Open with" bar on its own. I tested it by trying to download a new .aspx file, and it worked! I hope you have success.
lori1013, Your suggestion worked. It took trying 5 times as you said, then when I tried to open it the 6th time it opened itself without the other steps. Wierd! I had tried what you suggested before but only 1 time. Why would you try 5 times? Why does this work? I really don't care about the answer to these last 2 questions, I'm just so thankful that you tried it, told me and that it works now. Thank you, thank you, THANK YOU!
I've had this problem for 3 years. And I can see that questions were posted by others in 2006. The only answer that works for me is to ignore the Firefox error message. Save the document from downloads onto my desktop. Change the .ashx ending to .pdf and confirm that. Then it opens in Preview.
Neither the Shockwave nor the Adobe tricks work on my mac.
How come Firefox can has not dealt with this error 4 years on and more "modernising" websites use this format? Please?
Great ideas, I'm sure, but the problem is with ".ashx" files, not .aspx files.
If somebody finds a method for Firefox to display these files, I'm sure it would be really useful for all us Mac users out here.
The original question is really for .ashx files (not .aspx files). Although the .ashx file is a pdf file, it cannot be opened by Preview. So I followed one of the suggestions above (thanks to lori1013) to associate the extension .ashx with Adobe Reader. (save the file, right-click on the file name, select "Open With", find Adobe Reader, check the "Always Open With" box).
Now when I click the link on a web site with a .ashx file, Firefox warns me it may be an application and will be opened by Adobe Reader. I click on Open and it works!
I had just switched to Firefox on my iMac and was having the same problem and your solution worked for me. But, as you say, if this problem has been around for four years why hasn't it been fixed? I will be forced to try Chrome or worse, go back to Safari. All my online bill pays use .aspx files.