Flows suddenly failing - Add hours function

[RodM]

Syntax:

formatDateTime(addHours(outputs('Compose'),-4),'MM/dd/yyyy HH:mm')

I'm using this function to subtract time from Microsoft Forms responses to match local time. My flow worked flawlessly up until 10 minutes ago when there have been several failures due to the error below. I believe the description is saying my syntax is incorrect.

Please help!

Error:
Flow Run Failure: One or more fields provided is of type 'Null'.

InvalidTemplate. Unable to process template language expressions in action 'Add_a_row_into_a_table' inputs at line '1' and column '16902': 'The template language function 'addHours' expects its first parameter to be a string that contains the time. The provided value is of type 'Null'. Please see https://aka.ms/logicexpressions#addhours for usage details.'.

[RodM · Accepted solution]

Please ignore. It seems Microsoft was having issues because its now resolved itself with no changes.

[efialttes]

Hi!

The problem seems to be... outputs('Compose') is null i.e. empty.

So you need to check which value is currently assigned to your 'Compose' action block.Assuming you assigned a Forms response to it, it means somebody did not answer the question, and you get a null value instead of a date modelled as a string in ISO 8601 format.

So, either you mark the question as mandatory, or you add extra logic to replace null and handle a default date instead.

Hope this helps

[RodM]

Yes, the issue was traced to the Microsoft Forms server.

All fields on the form are required (not optional). Downloading the Excel sheet with the response data, those entries are gone. There are 17 response IDs missing.