Hi @OwenBale and @declanryan (@Declan2 )
Could you try downloading lesson 5, the lesson 6’s (if they don’t show up as lesson 6 then just try and download anything between lesson 5 and 7) and Vocab 10. For good measure, download lesson 1, and lesson 16 too.
We recently uploaded new versions of the lessons you’re having problems with, so perhaps it’s related to that.
James
Dwi yn hapus iawn. Diolch yn fawr Owen. I am not mad!! I will try anything!
James,
Lesson 1 and 5 good, 6.1 and 6.2 failed, 6 bonus good (appears twice) 7 good 16 good but vocabulary 10 failed,
I am so releaved there is hope!
Thanks
Declan
Thanks for checking those, Declan - James seems to be on a fruitful path of inquiry here, so fingers crossed he’s going to be able to crack the mystery for us! 
@declanryan
could you take a screenshot showing the lesson 6’s please and upload it here, or private message it to me
To take a screenshot:
Press the Power button on the top right corner of your device and at the same time, press the Home button. The screen flashes, and if you have sound enabled you will hear a camera shutter sound.
The picture is saved with the rest of your images in the Photos App on your device.
This is a long shot, but is anyone who’s having trouble downloading running iOS7 or earlier?
Oh… scrub that question! I am able to re-produce the problem by deleting my installed copy, and re-installing. Before deleting, it was working fine, and now I’m getting the downloading error.
So, if yours is working - don’t re-install right now!
I am sorry TBS but I cannot drag/paste or use the attach icon above do you have another address that I can send the image to? Thanks for the tip about screenshots. Amazing!
Sorry James I have just found your name on the message from Aran. I cannot use the attachment icon above can you give me another email to send the screenshot to?
Declan
We’ve got some of our best techie-minded volunteers grappling with this right now, so fingers crossed you won’t need to suffer for too much longer - it’s looking increasingly likely that the issue is being caused by our security certificate, and we might be able to find a short-term workaround while we deal with the medium term issues.
Thank you very much once again for letting us know about it, and helping with the work of tracking the problem down
Here’s Declan’s screenshot:
Thanks @Declan2
Could we also have a screenshot of the course six lessons, but without the error message over the top
Diolch
Here it is 
Ok, I think I have a work-around (actually two).
When you re-install the app, there’s a glitch where it doesn’t select the “Active Course” properly. To fix this, go to the “Settings” tab, and just under “Active Course” will be an empty box. Touch that box, and it will bring up a list, with Course 1 at the head. Select that, and tap Done. Now go to the Lessons tab, and try to download any lesson. It worked for me after making that settings change.
Now, you may be wanting to access Level 2 and beyond, and have discovered that it won’t let you login. Do this: when it rejects your login, it has left the keyboard still up. Hit Done to close the keyboard. Now, hit the “Login” button (again). This time, it will (hopefully) succeed (it did for me).
Update: I tried uninstalling and re-installing the app again. Just selecting Course 1 isn’t quite enough to get things working. What did work was to select something else in the list, then select Course 1 again. That worked (and matches what I did when I was testing this workaround earlier).
Was just coming here to recommend lewie’s excellent workaround, and realised he’d already posted it. Nice one!
Thanks to lewie and our other most excellent volunteers, who’ve all been a brilliant help in the investigation of this problem this afternoon/evening! 
Summary: Go to settings, press on the probably-empty box at the bottom, choose something that isn’t the course you want, then choose something that is the course you want. Then go back to lessons and it should work.
Please continue to let us know if you still have problems 
Update! There was a fix I tried to put in place just earlier, which didn’t work during our testing, but I think I’ve just worked out why, and it seems to be working for us now. So, please try just downloading stuff without the workaround above, and let us know if it works! And if not, then go ahead with the workaround
Lewie and Kinetic,
It works! I am so impressed! Firstly that the times of your emails were 0142 and 0536! And secondly that the solution was so amazingly simple. I am sorry not to have worked that one out without all the bother!
I think you need to sleep! its not healthy to work all night!!
Best wishes,
Declan
Glad it’s working for you! But I can’t take credit for an all-nighter - I live on the west coast US, so I slept just fine last night .
Thanks all the app is much better, I am reall grateful. It is only a small point but the lessons are inclined to delete themselves and if you switch it off mid lesson the lists reverts back to lesson 1. It is only a minor inconvenience but shows that something has changed from where it was 2 weeks ago.
Thanks for the heads up on that - we don’t actually have access to the code itself at the moment, which was developed by a volunteer who is very pressed for time in terms of further development - so we’re currently thinking in terms of a new app where we will have access to the code - in fact, Jeff has been doing some work in that direction very recently