Same here, another stunning release from TP link, now my entire network is useless, great job

I did try with Omada to downgrade the firmware. Omada can't do that because it looks like it has no connection anymore. I did a factory reset, try to adopt the router again. It keeps failing. After a second factory reset I downgraded the firmware and adopted it again. Now my network works again! But the new firmware is useless in combination with Omada. 

Edit: it looks like the firmware is not working with Omada 5.7.4 (Linux). But why does Omada 5.7.4 notify me to install firmware that is not compatible... 

When will a non-Windows version of Omada 5.8.x released?

This is totally unacceptable..., once the router quits, the entire network is usless....

I had to manually hard reset the router, connect to it directly, then downgrade the firmware...

Next, reconnect the router and connect to the OC200 directly with a laptop on a static IP

IMPORTANT: If you do not set a static IP on your OC200 you will be screwed..., make sure you set a STATIC IP .... (if you don't do this, then loss of router = loss of DHCP = loss of access and factory reset time...)

Once logged into the OC200, the router displays as PENDING but every adopt attempt I tried (x5) failed.

This is because of another major drawback of Omada...

If devices move away from the default LAN address of 192.168.0.x then nothing works...., I use 192.168.10.x as by default LAN, so in order to readopt the router I have to:

1) Change the static IP of the OC200 to the default subnet (eg. 192.168.0.2)

2) Change the static IP of the connected laptop to this subnet

3) Reboot the router

4) The router will now appear in as PENDING in the controller UI

5) Adopt the router

Here is where it gets trickey, because once the router is provisioned, it will change its IP back to the subnet 192.168.10.x, but there is no way to know when this is, because the controller is now on a different subnet, so I must

1) Wait an unspecified amount of time until I 'think' the router has been provisioned

2) Change the static IP of the OC200 controller back to the 10.x subnet

3) Change the static IP of the laptop back to the 10.x subnet

4) Attempt to relogin to the controller

Then, if I'm very lucky, I get my network back.

What part of this priocess is Omada's 'Zero Touch' provisioning ?

The entire process is a hot mess, and what to TP-Link do about it..., sod all !

  @Tescophil I am having the exact problem. My network is completely nonfunctional at this point .

TPlink - what is the proposed solution here? This is completely unacceptable .

  @SuperUserOne 

Same friggin issue. Tplink let us down with this upgrade. My whole network is down including all my tplink tapo ip camers (24 pieces c320ws cameras) i cant even access my OC200 now

The only way to join the network is configure the device to a static ip address (PC or gadget) but still cant access the OC200. DHCP doesnt work and will not hand out ip addresses. This is really frustrating!!!!!  COME ON TPLINK, YOU ARE BETTER THAN THIS!

Upgraded ER605 to 2.1.0

No issues. 

System came back up after 5min.

All is good.

  @PRAXXUS which version of Omada do you use?

The combination of the new firmware and Omada 5.7.4 doesn't work.

Same for me, I had an SDN on debian. I upgraded it to 5.7.4 and then upgraded a router, and no problems. I did the upgrade on a client router, and there catastrophe, the router cut in loop and no more dhcp.  I went to my client, replaced the router and did not put it back on SDN. 
 

I'm on OC200 version 5.7.6 and had the provisioning loop problem.

A fundamental issue here is when the router goes wrong on your Omada network, AND you follow the default guidance i.e. DHCP for everything, then its game over. Once the router falls over EVERYTHING on the network will stop working, with no way to access the controller, or any other device to attempt recovery. The only way forward from here is to factory reset the controller and basically start from scratch.

If you alter the default IP address subnet of the router, you will also be stuffed. This is because even though a controller on a different subnet to the default of 192.168.0.1/24 will be able to see the router, it will not be able to adopt it.

There is a big disconnect on how these devices are managed. We are encouraged to setup a management VLAN on all devices, but this simply DOES NOT WORK. If you move the OC200 to a management VLAN, again, the router cannot discover the controller. There is some contrived guidance in the FAQ's attempting to resolve this ( https://www.tp-link.com/uk/support/faq/2814/ ), but once you get to step 5 in this guide it FAILS.

I currently have a 'non standard' default LAN range of 192.168.10.1/24 and a management VLAN on 192.168.200.1/24. The management VLAN has all the switches and AP's on it, whilst the OC200 is on a static IP on the default LAN along with the router.

I'm seriously thinking about reconfiguring my entire network after this, so that all the Omada devices are on the default LAN with the factory default IP address range of 192.168.0.1/24, then move all the other devices currently on the default LAN to a new VLAN. This way, when the router inevitably needs a factory reset again, it should just get adopted automatically by the controller to restore the network. (the default LAN effectively becoming the Management LAN, that will hopefully _actually_ manage the network)

I have just reset my client's router which is now in 2.1. I don't even have access to the router anymore, I just have a blank page.

Tp-link will have to compensate, or offer us Mikrotik :) 

Well it works in standalone mode, it came from the browser.