After 4.7-update, site is lost, no chances to re-login

If i try to re-login or to visit my homepage, the browser shows a blank page.

This usually means there’s a PHP error somewhere. Edit your wp-config.php file so that WP_DEBUG is defined as true. Re-load the blank page. This time there should be error messages telling us what and where the problem is.

That other output are things that should be addressed, especially the Warnings. They would not stop your site from loading though. Warning level errors often indicate related code is not functioning as intended.

Obviously a Fatal Error is what is crashing your site. pomo/streams.php is used to load translation files into memory. Translation files shouldn’t be so large that loading into memory would be a problem. Do you have any idea what file might be loaded that is so large as to overrun memory? Another possibility is some code is stuck in an infinite loop and the file load just happened to be the one operation that kicked the process over the limit. I’m guessing the latter.

It’s not unheard of for problems to arise on hosted servers that were no problem on localhost due to differences in server configuration. We need to narrow down the source of the problem. This is normally done by deactivating all plugins and switching to the twentysixteen theme. Reinstating each, one by one, will eventually reveal the problem entity.

Of course, since you cannot log in, that would be hard to do. We can disable plugins and switch themes through FTP or your hosting account’s file manager. Go to the wp-content folder and rename the plugins and themes folders. Create a new themes folder and copy (not move!) the twentysixteen folder and its contents from the renamed themes to new themes. Depending on your FTP client, copying may be difficult. You might have to download the twentysixteen files and upload back to the new folder. Renaming forces WP to use the only theme in themes and to deactivate all plugins.

You should be able to login now. Your site will be messed up due the theme change and lack of plugins. Don’t worry, it’s temporary and better than the “White Screen of Death” aka WSOD 😉

Once you’ve logged in, use FTP to rename the new themes folder, and rename the original folders back to their proper names. In the back end you can now restore your original theme. Reload your page. If your site doesn’t crash, proceed to activating your plugins one by one, most important first. Reload after each one.

When your site crashes again, you’re going to need to do the whole renaming thing again. Make note of the last activated entity, you don’t want to activate that one again! You should be able to login and restore all of your previous setup except that one entity.

Take up the site crash issue with the author of that entity, or find another one that works similarly, or do without, or debug the code yourself. Good luck!