@sgunhouse I was able to open the file with a file manager so it is present and intact. When I search the web for information on access to the the sd card under android v. 11, I see Many problems reported that appear to be related to changes in security protocols in that version. It would appear that I am out of luck unless/until Opera or some other browser figures out how to deal with this issue. Since I doubt that many phone users are interested or have need to install and run a web site from the sd card of their phone, a solution will be not likely be considered worth pursuing. Indeed, with increased coverage using mobile data to connect to the internet and fewer worksites in truly remote areas in my future, this need is not as critical for me as it was a few years ago. However, it is still frustrating to have something that was working perfectly discombobulated by arbitrary forced changes in operating systems. Thus, I will remain on the lookout for any solutions that may be forthcoming.

@leocg I tried Chrome earlier today without success. I originally got this working several years ago on a Galaxy S5, experimenting with information available on the web at the time. When I got it to work with Opera, I was delighted and never tried anything else. Happily, the same file path worked on the A5 for more than a year.

@sgunhouse I was able to open the file with a file manager so it is present and intact. When I search the web for information on access to the the sd card under android v. 11, I see Many problems reported that appear to be related to changes in security protocols in that version. It would appear that I am out of luck unless/until Opera or some other browser figures out how to deal with this issue. Since I doubt that many phone users are interested or have need to install and run a web site from the sd card of their phone, a solution will be not likely be considered worth pursuing. Indeed, with increased coverage using mobile data to connect to the internet and fewer worksites in truly remote areas in my future, this need is not as critical for me as it was a few years ago. However, it is still frustrating to have something that was working perfectly discombobulated by arbitrary forced changes in operating systems. Thus, I will remain on the lookout for any solutions that may be forthcoming.

@leocg I tried Chrome earlier today without success. I originally got this working several years ago on a Galaxy S5, experimenting with information available on the web at the time. When I got it to work with Opera, I was delighted and never tried anything else. Happily, the same file path worked on the A5 for more than a year.

I have a large website stored on the "external" sd card of my Samsung Galaxy SM-A50 5U. I have long been able to browse the content this site off-line using the file path:
File://localhost/storage/3061-3035/OFPWesite/startfile.htm
It is critical for me to have access to the thousands of images in this web when I am working in remote areas in the field without internet or phone data coverage. Due to the Covid 19 pandemic I did not access this internal web for quite some time and when I tried recently, the message returned was "Access to the file was denied." The current android version on my phone is 11 but it is quite likely that the version installed when I last successfully addressed the internal web was a previous version. I suspect that a change in security protocol may be the problem. I have not been able to find anything current on-line that deals with anything quite like this this issue. I hope someone may be able to suggest a solution or work-around.