I was having the same issue with IP-1.5.3 (se: https://community2.invoiceplane.com/t/topic/4844) and I am still getting the same error with IP-1.5.5.
I have enabled online payments and have added PayPal Express and Stripe as payment providers. I have added the correct details for both providers and used live/production API keys for both.
However when I go to the guest URL for an invoice (upaid, of course) and click on the ‘Pay Now’ link, all I get is a blank page.
I can find no errors in chrome developer console and nothing that suggests an error or problem in /application/logs.
Application log:
DEBUG - 2018-01-27 23:28:26 → UTF-8 Support Enabled
DEBUG - 2018-01-27 23:28:26 → Global POST, GET and COOKIE data sanitized
DEBUG - 2018-01-27 23:28:26 → Payment_Handler MX_Controller Initialized
DEBUG - 2018-01-27 23:28:26 → Config file loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/config/invoice_plane.php
DEBUG - 2018-01-27 23:28:26 → Encryption: Auto-configured driver ‘openssl’.
DEBUG - 2018-01-27 23:28:26 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/modules/settings/models/Mdl_settings.php
DEBUG - 2018-01-27 23:28:26 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/controllers/…/modules/layout/controllers/Layout.php
DEBUG - 2018-01-27 23:28:26 → Layout MX_Controller Initialized
DEBUG - 2018-01-27 23:28:26 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/modules/invoices/models/Mdl_invoices.php
DEBUG - 2018-01-27 23:28:26 → Total execution time: 0.0164
DEBUG - 2018-01-27 23:30:31 → UTF-8 Support Enabled
DEBUG - 2018-01-27 23:30:31 → Global POST, GET and COOKIE data sanitized
DEBUG - 2018-01-27 23:30:31 → Payment_Handler MX_Controller Initialized
DEBUG - 2018-01-27 23:30:31 → Config file loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/config/invoice_plane.php
DEBUG - 2018-01-27 23:30:31 → Encryption: Auto-configured driver ‘openssl’.
DEBUG - 2018-01-27 23:30:31 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/modules/settings/models/Mdl_settings.php
DEBUG - 2018-01-27 23:30:31 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/controllers/…/modules/layout/controllers/Layout.php
DEBUG - 2018-01-27 23:30:31 → Layout MX_Controller Initialized
DEBUG - 2018-01-27 23:30:31 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/modules/invoices/models/Mdl_invoices.php
DEBUG - 2018-01-27 23:30:31 → Total execution time: 0.0764
DEBUG - 2018-01-27 23:30:37 → UTF-8 Support Enabled
DEBUG - 2018-01-27 23:30:37 → Global POST, GET and COOKIE data sanitized
DEBUG - 2018-01-27 23:30:37 → Payment_Handler MX_Controller Initialized
DEBUG - 2018-01-27 23:30:37 → Config file loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/config/invoice_plane.php
DEBUG - 2018-01-27 23:30:37 → Encryption: Auto-configured driver ‘openssl’.
DEBUG - 2018-01-27 23:30:37 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/modules/settings/models/Mdl_settings.php
DEBUG - 2018-01-27 23:30:37 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/controllers/…/modules/layout/controllers/Layout.php
DEBUG - 2018-01-27 23:30:37 → Layout MX_Controller Initialized
DEBUG - 2018-01-27 23:30:37 → File loaded: /home/rhyshay1/public_html/dev.invoice.pickle-it.co.uk/application/modules/invoices/models/Mdl_invoices.php
DEBUG - 2018-01-27 23:30:37 → Total execution time: 0.0224
Any ideas ?
Thanks