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I had an 800 an odd day streak when suddenly the programme keeps freezing. Not on any particular question it can be 5, 11 or another. It has been like this since last Monday. I have reinstalled Duolingo and closed my mobile but nothing works, so frustrating.
Christine
Thomas.Heiss
iOS or Android?
What course?
What Section/Unit/Level/Lesson?
Have you rebooted your phone BEFORE you installed the new version?
Q: Is the www.duolingo.com/learn web portal working any better for you?
It's probably an internal Duolingo bug...
iOS:
Multiple bugs got introduced according to the /r/Duolingo Reddit channel over the past weeks/months; it's not a very reliable platform anymore.
With Duolingo you're the alpha-/beta tester, constantly.
Rolling out of new app versions every 7-14 days..that's just a joke.
Is similar to directly rolling out the master/trunk/head developer code without any further QC and functional testing.
A very stable code requires a separate branch with several weeks or months of detail testing (QA department) and only then to release a new version it to the public.
Somehow I'm not surprised that new bugs constantly are showing up.
Maybe they added too many things to a course too fast (like new challengeTypes).
People are leaving out too many details incl. OS versions.
And without any debug file and StackTrace and detail error message not much can be sent to the developers in a bug report from a user perspective.
DL staff unfortunately doesn't give out much info how to track down technical errors or how to enable a debug mode and where the file is written.
Try to SKIP over a specific lesson number or use a different platform (e.g. Web, Android) or use a much older - more stable version (on Android).
Native | 
Upper-B2 (BritishCouncil) | 
L25 (Duo) / A2 (6+y, McGraw-Hill) - Learning (Busuu): 
(A1 McGraw-Hill) | 
(interm.)
Im getting the same, repeatedly, and its driving me crazy. I’ve tried all the fixes suggested, checked my phone for capacity etc etc, the only thing I found that worked was going into Duo via the web rather than my app, which would let me get past the exercise it had stuck in, then it would work fine on the app again once I got past the point on the web version where it had seized n the app, almost like it was unblocking it. But today, I couldn’t even load the exercises on the internet version! SO FRUSTRATING!! Come on Duo, you can do better than this. Your app is so flakey it’s getting unusable! 
Thomas.Heiss Native | Upper-B2 (BritishCouncil) | L25 (Duo) / A2 (6+y, McGraw-Hill) - Learning (Busuu): (A1 McGraw-Hill) | (interm.)
Thomas.HeissDepending on the course it might be new challengeTypes which are buggy in the mobile app.
Maybe an older app version works on Android but not if specific (new) challengeTypes crash the app.
Native | Upper-B2 (BritishCouncil) | L25 (Duo) / A2 (6+y, McGraw-Hill) - Learning (Busuu): (A1 McGraw-Hill) | (interm.)
Thanks for the reply. I try deleting and re-downloading the app when this happens, but it doesn't always resolve the issue., including earlier this week when it was two days before I was able to get back in to progress on with the exercises. I had to make do with reviewing old exercises and practices to keep my streak going. It resolved itself two days later. This really isn't good enough Duo!
Thomas.HeissThis probably won't solve your Duolingo issue:
But keep in mind that sometimes it helps to do a reboot with the phone to free up resources.
I noticed that sometimes my Android 11 phone locks up a bit with some Java heap VM stuff and the RAM isn't fully freed even some tools show enough Ram (1.5-2Gb) should be available.
It might be only the one or other app/game which causes this erratic state.
Nevertheless it's a good idea to reboot a smartphone from time to time.
Native | Upper-B2 (BritishCouncil) | L25 (Duo) / A2 (6+y, McGraw-Hill) - Learning (Busuu): (A1 McGraw-Hill) | (interm.)
Thomas.HeissOn Windows 11 I noticed that the fastboot is turned on by default.
Which means that the OS will never do a complete startup; it only freezes its memory to disk with hibernation mode.
So even on a laptop you need to disable this setting if you want to shut it down regularly...or...you need to frequently hit the Reboot button and not to only power off if Fastboot option is enabled (by default).
This alone of course won't help if a specific Duolingo lesson and challengeType is freezing or crashing.
Nevertheless a clean memory and rebooted system often helps to run some apps (like browsers) more stable and not to overload the Cpu with stuck (background) processes or Antivirus programs or Spam shields.
If not enough memory is available or the Cpu is stuck at 50/90-100% forever with specific processes it is a really good idea to reboot if you haven't freshly started a device for a longer time.
Native | Upper-B2 (BritishCouncil) | L25 (Duo) / A2 (6+y, McGraw-Hill) - Learning (Busuu): (A1 McGraw-Hill) | (interm.)
Davey944676
My (pretty old, but generally OK) android tablet keeps freezing too, but only on one language (Ukrainian) when I mess up too much and have to do a practice for a heart to continue. It freezes at the last one.
I have to switch and do a lesson in another language to continue. 
British Native....Learning Polish 
, Russian 
, Romanian 
, Ukrainian 
, French , Welsh 