Development Errors Result in Too Many Redirects

[astorm]

When an error/uncaught-exception occurs Magento 2, with developer mode on, the current system behavior is to redirect the user to the home page, and then the home page will display the error/exception message.

This often creates a "too many redirects" problem

The "too many redirects" problem happens if

• There's an error during Magento's homepage loading
• There's an error with/in an observer for an event that fires on every page

There are myriad ways this can and will crop up during regular development, but the easiest way to reproduce the problem is

1. Configure your system so developer mode is on
2. Open the app/code/Magento/PageCache/etc/events.xml file
3. Find the Magento\PageCache\Model\Observer\RegisterFormKeyFromCookie text
4. Temporarily simulate a mis-configuration by changing this to Magento\PageCache\Model\Observer\RegisterFormKeyFromCookiee
5. Clear your configuration cache
6. Reload any page in the system

Expected Behavior: The browser displays the text, along with a Stack Trace

Class Magento\PageCache\Model\Observer\RegisterFormKeyFromCookiee does not exist [] []

Actual Behavior: Browser gets caught in a redirect loop, resulting in a "This webpage has a redirect loop" error

While error handling is a complex problem, at minimum it's reasonable for a developer/programmer to expect their PHP error be displayed on the screen when developer mode is enabled. With error handling being such a multifaceted thing that touches many different aspects of the system, this sort of change is probably best handled by the core and/or development leadership team. If not coded by them directly "the right" solution ultimately needs to come from a central authority.

While this is also undesired behavior for non developer mode, the issue has not been researched there, and if present may require a different solution in that context.

[mazhalai]

@astorm thank you for reporting this issue. We have created ticket MAGETWO-37969 to investigate this issue.

[antonkril]

I saw this behavior confuse all developers new to M2 on hackathon. So I think it should be high priority.

[piotrekkaminski]

Fully agree - needs to be fixed

[vpelipenko]

@astorm, fix is already available on here on public GitHub. Are you OK with provided changes?