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This is the second time I am getting this error. The first time the only fix I found was to recreate my project and all of the files, but this time it is not an option.
I am getting an "Unrecognized tag prefix or device filter 'asp'" error on my asp tags in a .ascx control. Everything was working fine yesterday, but today when I started the project this occurred. Some things to note:
This is really a big problem for me as the intellisense is not working and makes my work a lot harder.
Thank you for your time, I will be happy if you have any suggestions for me. You can ask me for further information, and I will gladly provide it.
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Assuming the UC and project builds ok? And assuming we are using a project (.sln) and NOT a web site (which means you ARE NOT using file->open web site, but ARE using file->open project).
Open the aspx page in question desinger's file.
And delete all of the code inside - leave JUST the starting part of the header.
So, it looks like this:
So, now save above, and close.
Now open the markup file (aspx page). Simple hit enter, or "dirty" the aspx page (then save, then close). (so just hit enter a few times, or modify the page, again, save and close.
Now, Build->Rebuild Solution.
This will re-generate the designer file, and you should now find that both the designer, and even inteli-sense in the page markup will recognize the user control.
Tried the above solution. The designer file got regenerated correctly with all the controls, correct names, etc., but the issue still stands.
Yes, the UC and project build fine.
Yes, it is a solution (.sln) with a webforms project and a website inside of it (the control is in the webforms project).
Thank you, and if you have any other suggestions I will be grateful.
Update: I upgraded the other computer's VS to 2022 from 2019 and now it has the same issue. I tried downloading 2019 again, but it didn't work so now both computers have this broken.
You should report this problem to Microsoft using the feedback button, top right corner of the IDE.
The issue got fixed. I don't know how, I don't know why. I was filling my issue to Microsoft, one moment it wasn't working and the next it was fixed. It was like they heard. I don't know what to say to anyone with the same problem.
Thanks everyone for the support.
Well, this issue been around for well over 10 years. I don't think the issue is new, or even limited to vs2022.
However, before you try the steps I outlined above?
Do a clean project. Then open the project folder, open "bin" folder, and ctrl-a, and then hit del key to delete.
Now, do a project re-build all.
The other thing to try is to switch the web forms designer back to legacy settings. That is this setting:
tools->options->Web Forms designer
There are "many" comments (over the years) about how switching from ANY CPU to x64 or x86 also fixes this issue. However, what REALLY is occurring is a new bin sub folder gets created when you switch the CPU settings. Thus, in effect you starting with a clean bin folder - and hence the issue goes away.
So, close the aspx page in question. Delete the bin folder, do a re-build all. Now, open the aspx page - it should work.
The force re-build of the designer file as I outlined above also often helps.