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Datetime string must match ISO 8601 format.'.

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Posted on by CU30072308-0

Flow error: Unable to process template language expressions in action 'Create_item' inputs at line '0' and column '0': 'In function 'convertTimeZone', the value provided for date time string '"5/5/25 8:15 AM"' was not valid. The datetime string must match ISO 8601 format.'.

Note: I followed an online tutorial to build my flow. I have no coding knowledge. I am having an issue with the date / time fields. I suspect the flow will also fail for a following number column (Duration) as well.

Flow function: An uploaded CSV file writes working hours to a sharepoint list. I have tried wrapping the split(item() expression in a format date time function, (as shown in the note above create item) but that is not working. Any help would be greatly appreciated. I have spend hours trying to figure it out, but working with arrays is way beyond my knowledge base.

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Chriddle 8,443 Super User 2025 Season 2 on at

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Although it doesn't conform to ISO 8601, your date format basically works. Don't split it.
Your problem seems to be the double quotation marks. Simply remove them.

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CU30072308-0 25 on at

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here is my updated expression: formatDateTime(item()?[1],'yyyy-MM-ddTHH:mm:ss') The flow is still failing. The error now

Unable to process template language expressions in action 'Create_item' inputs at line '0' and column '0': 'The template language expression 'formatDateTime(item()?[1],'yyyy-MM-ddTHH:mm:ss')' cannot be evaluated because property '1' cannot be selected. Property selection is not supported on values of type 'String'. Please see https://aka.ms/logicexpressions for usage details.'.

Any suggestions?

Here is my list headings if that helps. At some point in trying to get this to work, I tried adjusting the content type of column 1 to text, that's why the time is missing. The CSV data resembles column 2.

0 1 2 3

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Chriddle 8,443 Super User 2025 Season 2 on at

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formatDateTime(item()?[1],'yyyy-MM-ddTHH:mm:ss')

You haven't split the item here.

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tom_riha 10,185 Most Valuable Professional on at

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Hello @CU30072308-0,

you can use the expression parseDateTime(...) to convert date in any format into an ISO format as explained in this article.

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CU30072308-0 25 on at

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I used copilot to try and help solve this. This was copilots suggestion

Thanks for testing that and sharing the result — this confirms that Power Automate is not able to parse the date string "5/5/25 8:15 AM" directly because it’s not in ISO 8601 format, and convertTimeZone only accepts ISO 8601.

✅ Best Solution: Preprocess the CSV to Convert Dates

Since Power Automate doesn’t support custom date parsing formats like 'M/d/yy h:mm tt', the most reliable solution is to preprocess the CSV and convert the date strings into ISO 8601 format before using them in your flow.

I can help you do this automatically by:

Reading the uploaded CSV.

Converting the "Clocked In" column to ISO 8601 format (yyyy-MM-ddTHH:mm:ss).

Providing a cleaned CSV you can use in your flow.

Copilot provided the following file for me. The flow worked with the file that was provided, but it kind of defeats the purpose of a flow that will process the default CSV file. I'm at a loss ???

I'm attaching the cleaned file in hopes that someone will understand what the issue is.

Cleaned_CSVExport...

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