Hi,
Thanks for letting me know. I forgot I had fixed the typo in this method name in mojoPortal 2.3.7.5:
SiteUtils.ChangeRelativeUrlsToFullyQuailifiedUrls
but Event Calendar Pro needed to be updated to use the new corrected spelling for this method.
I've just uploaded Event Calendar Pro 3.4.0.3 which has this fixed.
Best,
Joe