# How I worked around startup issues with pynq z1 **URL:** \ **Category:** Support\ **Created:** [December 2, 2019, 7:33pm UTC](https://discuss.pynq.io/t/how-i-worked-around-startup-issues-with-pynq-z1/713 "2019-12-02T19:33:52Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![magnus0re](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/magnus0re/32/228_2.png) [@magnus0re](https://discuss.pynq.io/u/magnus0re)\ **Post date:** [December 2, 2019, 7:33pm UTC](https://discuss.pynq.io/t/how-i-worked-around-startup-issues-with-pynq-z1/713/1 "2019-12-02T19:33:52Z")
I wrote the image to the SD card, inserted it. But jupyter only showed a blank screen. after seeing that the jupyter service crashed after some time, I decided to run it manually, only to get ```auto Exception: You must define the 'cookie_secret' setting in your application to use secure cookies ``` when connecting to the server. Turns out, something was wrong with the config… after some googling I figured out it had to do with the tornado security. So to hack a fix for this, I changed /home/root/.jupyter/jupyter\_notebook\_config.py I uncommented the line and added the b’anything’ c.NotebookApp.cookie\_secret = b’anything’ and tested if it worked by running jupyter-lab --allow-root as root This worked for me. ---
**Author:** ![cathalmccabe](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/cathalmccabe/32/3348_2.png) [@cathalmccabe](https://discuss.pynq.io/u/cathalmccabe)\ **Post date:** [December 3, 2019, 11:36am UTC](https://discuss.pynq.io/t/how-i-worked-around-startup-issues-with-pynq-z1/713/2 "2019-12-03T11:36:28Z")
Thanks for sharing this. Could you let us know the following?: - Which version of PYNQ are you using? - Which OS/Browser? - Which IP are you using to connect to PYNQ and is your board connected to the internet? Cathal ---
**Author:** ![magnus0re](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/magnus0re/32/228_2.png) [@magnus0re](https://discuss.pynq.io/u/magnus0re)\ **Post date:** [December 6, 2019, 2:31pm UTC](https://discuss.pynq.io/t/how-i-worked-around-startup-issues-with-pynq-z1/713/3 "2019-12-06T14:31:32Z")
I’m using pynq z1, connected with an ethernet-usb dongle to my windows 10 laptop using a version 2.5 image from xilinx downloads. Note that after changing the setting, I can connect normally from boot, and everything seems to work fine. – Magnus ---
**Author:** ![blurpy](https://avatars.discourse-cdn.com/v4/letter/b/958977/32.png) [@blurpy](https://discuss.pynq.io/u/blurpy)\ **Post date:** [April 4, 2020, 4:45pm UTC](https://discuss.pynq.io/t/how-i-worked-around-startup-issues-with-pynq-z1/713/4 "2020-04-04T16:45:24Z")
I had the exact same issue with my PYNQ Z2, using the PYNQ 2.5 image from Xilinx. Tried 2 different ways of flashing the SD-card with the image, and it was the same each time. Started up, no blinking LEDs, and jupyter crashing with complaints about that secret. I tried your solution and it worked. Then the next time I booted it up, it went into a reboot loop, so I suspected it was a power issue. Unplugged it from my USB-hub and plugged it directly into the computer, and it booted up without issue. And I also saw the LEDs flashing for the first time. So suspecting it might have been a power issue all along, I reflashed the SD-card to get rid of any changes I did and booted it up. And it worked perfectly. I can see it’s drawing upwards of 0.61 amps during boot, and maybe that’s too much for my USB-hub. Just posting this in case anyone else has this strange issue. Could be a simple solution. ---
**Author:** ![nickcamel](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/nickcamel/32/1650_2.png) [@nickcamel](https://discuss.pynq.io/u/nickcamel)\ **Post date:** [January 4, 2021, 8:41pm UTC](https://discuss.pynq.io/t/how-i-worked-around-startup-issues-with-pynq-z1/713/5 "2021-01-04T20:41:37Z")
I also had the boot loop problem which after power on / off went completely dead. So now power supply doesn’t even turn on the initial red led. So after your hint, I unplugged the power supply, changed jumper from REG to USB and used USB for power. It started up, but a minute or so after os booted up, it rebooted and is now in boot loop again.