I get the below error every time I call the send mail call. It locks me and the only way out is to kill Filemaker client. I get this error for years now since FM 16 on all the x64 versions. Switch To..., Retry, and X do not work as it keeps looping.
Up to now I was able to get around it because I was using the x32 version where the error does not happen.
Now I am moving to FM 19 as the FM 16 version has an EOL Oct-2020.
The FM 19 version comes only on x64 and I have no way avoiding it anymore. I thought that this will be fixed by now but apparently is not.