Problems using Android 8

Using "Traccar Manager" in Android version 8, I'm having trouble connecting to the server. No error appears and does not ask for username and password. Is someone doing something like that using Android 8?

Does it work in browser? If yes, it should work in the app as well.

I'm using the Traccar Manager / Client on my Zenfone 4 with Android 8 and there is no problem!

I have a similar problem. You can see something like this all the time.

ZUK Z2 Pro / ZUI 3.5.316 ST (Android 8.0)

Does it work in browser?

In the Chinese system browser: no (the same problem)
In (default) Firefox: yes.

I just checked in chrome, it also does not work.

OK, you would need to check Chrome browser console. You can do it from desktop browser.

cdnjs.cloudflare.com/ajax/libs/extjs/6.2.0/ext-all.js:22 Uncaught TypeError: Cannot read property '1' of null
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cdnjs.cloudflare.com/ajax/libs/extjs/6.2.0/ext-all.js:22 Uncaught TypeError: Cannot read property 'defaultConfig' of undefined
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    at Function.doProcess (cdnjs.cloudflare.com/ajax/libs/extjs/6.2.0/ext-all.js:22)
    at Function.process (cdnjs.cloudflare.com/ajax/libs/extjs/6.2.0/ext-all.js:22)
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    at cdnjs.cloudflare.com/ajax/libs/extjs/6.2.0/packages/charts/classic/charts.js:1
cdnjs.cloudflare.com/ajax/libs/extjs/6.2.0/classic/locale/locale-pl.js:1 Uncaught TypeError: Ext.onReady is not a function
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load.js:105 Uncaught TypeError: Cannot read property 'request' of undefined
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What version of Traccar are you using? I believe this issue has already been fixed:

https://www.traccar.org/forums/topic/traccar-manager-on-android-wont-load/

I am using version 3.11, that is, I need to upgrade to at least version 15.

In my case, is it better to upgrade directly to 3.15 or first upgrade to 3.12, then 3.13 ... up to 3.15?
Which way would be the safest?

Read upgrade guide.

Eh... 3.10 and default database of course :)

One day, I will install the latest Traccar and MySQL database. To touch linux I need strength, time and mental health.

You can upgrade straight to 3.15. Of course you don't need to downgrade to 3.3. I think you misunderstand how version numbering works. It's not a decimal number. It's major and minor numbers separated by dot.

https://en.wikipedia.org/wiki/Software_versioning

Yes, I noticed the version with a small delay :)

Is there any accurate tutorial to install MySQL (?) / InnoDB ?

Can i do that?:

1. Link
2. Link

Unfortunately, I use virtualized systems on my NAS. Currently I work on a Centos without a GUI.