Unable to fix malformed JSON

Try this link to further diagnose the problem:
https://mikejolley.com/2015/11/12/debugging-unexpected-token-in-woocommerce-2-4/
I eventually found this error:

ERROR: cannot generate bitcoin address for the order: ‘Failed to find/generate bitcoin address. Problem: Generated ’20’ addresses and none were found to be unused. Possibly old merchant’s wallet (with many used addresses) is used for new installation. If that is the case – ‘starting_index_for_new_btc_addresses’ needs to be proper set to high value’

and I seem to have fixed it by generating a new electrum wallet…