In Model/Gateway/Implementation.php there is line 308 that tries to mathematically add 100 to the order's increment id. This fails and results in an exception if the increment id has a non-numeric prefix or suffix. If a numeric value is really required, I suggest removing any possible prefix and suffix from the increment id first. Checkout magento/module-sales-sequence on how to fetch these values.
In Model/Gateway/Implementation.php there is line 308 that tries to mathematically add 100 to the order's increment id. This fails and results in an exception if the increment id has a non-numeric prefix or suffix. If a numeric value is really required, I suggest removing any possible prefix and suffix from the increment id first. Checkout magento/module-sales-sequence on how to fetch these values.