Editing the status of an order causes fatal error

[Robert-Held]

EXPLANATION OF THE ISSUE

Just updated to 2.6.2 (after a long run without any update) and added shipping zones as required. An order was placed successfully.
Now I want to edit that order in detail but when trying to change the order status, a fatal error occurs with this message:

Fatal error: Call to undefined method WC_Shipping_Flat_Rate::get_meta_data() in C:\xampp\htdocs\fslocal\wp-content\plugins\woocommerce\includes\abstracts\abstract-wc-order.php on line 491

This error does not occur, however, when I change the status in the order overview.

I can't find any direct link to a modification I made, so I don't know if this is an issue solely on my config. Below you'll find the status report for my local dev system.

Update: This error wasn't bound to editing the status. It occured when a shipping method was present when hitting the Save button.

STEPS TO REPRODUCE THE ISSUE

1. Go to the edit page of any order.
2. Change the order status.
3. Save the order.

SYSTEM STATUS REPORT

[REDACTED]

[mikejolley]

Definitely look at customisations because if you're adding a custom shipping method for example, it may lack this method.

[mikejolley]

Closing due to lack of feedback. Please perform basic troubleshooting steps (debug mode, disable plugin and themes) before replying further.

[Robert-Held]

Got it.
The cause was a conflict with an older version of the WooCommerce German Market plugin. It referred to WC_Shipping_Flat_Rate instead of WC_Shipping_Rate.

thanks

[Stef-S]

Thanks Robert! I currently have the exact same problem.
How did you fix it? Did you simply buy a renewal license of WooCommerce German Market?
Thanks in advance, Stefan.

[Robert-Held]

Hey Stefan, I hope you managed to cope with this problem in the meantime.
If not, here's what I did:
We currently cannot renew our license so I went to plugins/woocommerce-german-market/inc/WGM_Tax.php, line 223, where you find.
$new_shipping = new WC_Shipping_Flat_Rate( );
Change that to
$new_shipping = new WC_Shipping_Rate( );
WooCommerce' shipping system got a big change. That's why this breaks the old versions of WGM.

[Stef-S]

Hey Robert, thanks so much!!! This really helped a lot! Regards, Stefan

[xvostikk]

Thank you very much! I had the same problem, it helps.