If you run into this error while starting your web service, first take a look here:
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000g12vSAA&l=en-US#:~:text=This%20error%....
If that solution does not work, or does not apply to your situation, then it could be that LV is offended by one or more terminal connections on a VI connector pane. I've found that this can occur if you rename the controls or indicators that are already connected to terminals. Try un-connecting and then re-connecting the terminals.
This is with LV2019SP1. Not sure if it applies to other versions.
