1-click update from 1.7.7.7 to 1.7.8.7 not working

[Anchuron]

Hi there, 

I run 1.7.7.7 and found some security issues solved with the BLM vulnerability module. Even though this was fixed, I don't feel confident enough with my current version of Prestashop, so I want to update. I have the 1-click upgrade module but once I click on it now, just a blank page shows and there's no option to update. I tried deactivating all the modules, but keeps showing after the blank page. I cannot update and really think it is important for security reasons. Anyone can help?

[ComGrafPL]

Enable debug mode and try again. Will see if it show any issues.

[Anchuron]

It completely falls: 

(1/1) ContextErrorException

Warning: Cannot modify header information - headers already sent by (output started at /home/customer/www/tienda.anchuron.es/public_html/src/Adapter/EntityMapper.php:99)

in FrontController.php line 844

at FrontControllerCore->canonicalRedirection('https://tienda.anchuron.es/es/')in FrontController.php line 444

at FrontControllerCore->init()in Controller.php line 287

at ControllerCore->run()in Dispatcher.php line 518

at DispatcherCore->dispatch()in index.php line 28

[ComGrafPL]

Is it custom theme? If yes, switch to classic theme. Retry. Also, what's your PHP version? If below 7.4, change it to 7.4.

Edited August 25, 2022 by ComGrafPL (see edit history)

[Anchuron]

Falls again

[musicmaster]

Look in the var/logs directory for error messages.