Also in the Google Chromium when I see the code of the app, there is an error related to this error message.
So I build completely fresh Moodle servers (Moodle 2.8.5, Moodle 2.8.7 and Moodle 2.9.1) separately from my institution Moodle server, without any plugins or any themes. I download the Moodle mobile 2.0 from apple store for iOS device. I also use the android branch of Github repository link of moodlehq/moodlemobile-phonegapbuild (https://github.com/moodlehq/moodlemobile-phonegapbuild.git) and convert the app through Phonegap build online tool for android device. (The way I convert the Github repository link to an app can be seen at the end of the message.)
On Moodle 2.8.5 and 2.8.7, both iOS and Android devices have the same error messages as I mentioned above. On Moodle 2.9.1, both of the devices work fine, with no error message. It seems this error message only appears on Moodle 2.8.
Currently, my institution uses Moodle 2.8.7. Since folder activity is a basic activity in Moodle, many teachers are using this activity to organise their lecture resources. This error message issue really influences the behaviour of the Moodle mobile in my institution. In addition, this is the first time we introduces Moodle mobile to staff and students. As a result, it is very important to leave a good impression about this mobile app to users. Obviously, this error message is quite a big problem. I would be grateful if someone in Moodle mobile development could help to solve this issue as soon as possible.
The way I use to convert the app is:
First, get the link of moodlehq/moodlemobile-phonegapbuild in Github (https://github.com/moodlehq/moodlemobile-phonegapbuild), and choose ‘android’ branch. Then copy the URL of the page on the right hand side of the page.
Then, in the phonegap build, I paste the URL and branch in the form. Then Phonegap Build convert the app online.
The app I convert is here: https://build.phonegap.com/apps/1630284/builds
thanks for reporting this bug. I opened an issue to fix it:
I check the code change of this bug through the link that is mentioned in Moodle Tracker (https://github.com/dpaloucva/moodlemobile2/commit/7a8a05b2efe085296dea7a9ded1174b1bec0e162), as can be seen below. There is only one small change in core/components/course/services/course.js. I convert the original code of Moodle mobile 2.1 I get from Github moodlehq/moodlemobile-phonegapbuild/android repository with this change. However, when I open a folder in the Moodle mobile app, it still shows the error message. I wondered whether the change mention in the link is the only change I should have to fix the bug, or there are some other changes that Moodle mobile 2.1 in Github does not have affect the behaviour of the bug. In addition, the change is based on modlehq/moodlemobile2 repository. Does the work in moodlehq/moodlemobile-phonegapbuild? I hope that the code that will be released in this week does not have the bug any more.
Moodle Mobile project has 2 kind of files: development files and release (auto-built) files.
When we develop the app we work using the development files, where each controller/service/directive/whatever has its own file. These files are NOT included in the index.html, they aren't used by the app. When we want these changes to take effect, we "build" the release files (under build/ folder) so the changes made in the development files are reflected in the app. Initially we included these build files in the moodlemobile2 repository, but that caused some integration problems so we finally removed them. In the moodlemobile-phonegapbuild repository these build files are included, so there's no need to manually build them.
That means that if you want this change to take effect in the app you have to apply it to the build JS file. In here: https://github.com/moodlehq/moodlemobile-phonegapbuild/blob/master/build/mm.bundle.js#L4802
I hope I made sense