Date time zone issue

Question

I have created a rule to display date time 
 and currently my loacale of my profile is English (united states) I changed it to english (united kingdom) and now it is giving me this error Any idea why ? how to resolve it ?

Mike Schmitt · Answer

todatetime() expects an input string formatted presumably in your given time zone's format. if you changed your user locale but didn't update the formatting of the string you're passing it, then most likely it's now getting a string that it doesn't understand the formatting for. 
 I can't give much more specific advice than that since you haven't included your actual code and haven't included the source for the date/time string you're trying to pass into "todatetime()", both of which are important for figuring out what you'd need to change here.

Mike Schmitt · Answer

Is this rule expecting to receive a dictionary (which is what you're passing it here), as opposed to a bare DateTime value?

Mike Schmitt · Answer

but that's not relevant. you're still passing the entire dictionary returned by a!fromJson(), which would be like 
 { dateTime: <datetime value> } (or per Stefan's runtime example above: ) 
 So the issue is: this rule would need to understand that it's looking for a property named "datetime" from the value being fed into it, if you're trying to feed it the entire dictionary. It's crashing because it is not doing this. Otherwise you should be feeding just the ".datetime" property of the a!fromJson() result.

Mike Schmitt · Answer

yeah this would be what's needed except, as stefan mentioned, the dateTime stored in the JSON string must be in ISO 8601 format, i.e. yyyy-mm-dd. 
 For your example, where is the JSON string originally coming from? Are you generating it or is it getting generated elsewhere? Can you perhaps give some more overall context to your use case, so we can understand? It seems like we might have gotten a bit lost in the weeds, with respect to what your starting point is, and what you're trying to accomplish overall.