I've tested with does the string correctly however when post the plus sign of the timezone is replaced by white space

Stack400

   at sseConsulta1.CcTestOppwa2.ActionPostPayments(HeContext heContext, ICcTestOppwa2Callbacks _callbacks, String inParamAuthorization, String inParamentityId, String inParamamount, String inParamcurrency, String inParampaymentType, String inParampaymentBrand, String inParammerchantTransactionId, String inParamip, String inParamsurname, String inParamgivenName, String inParamcountry, String inParamshopperResultUrl, String inParamcustomParametersSIBSMULTIBANCO_PtmntEntty_, String inParamcustomParameters_SIBSMULTIBANCO_RefIntlDtTm_, String inParamcustomParameters_SIBSMULTIBANCO_RefLmtDtTm_, String inParamContentType, STPostPaymentsResponseStructure& outParamResponse)HTTP Trace:POST https://test.oppwa.com/v1/payments HTTP/1.1

User-Agent: OutSystemsPlatform

Content-Type: application/x-www-form-urlencoded

Authorization: [redacted]

Host: test.oppwa.com

Content-Length: 547

entityId=8ac7a4c879466f8e017953551b9d1246&amount=10.00¤cy=EUR&paymentType=PA&paymentBrand=SIBS_MULTIBANCO&merchantTransactionId=ABC12345&customer.ip=213.58.172.221&customer.surname=JOHN&customer.givenName=DOE&billing.country=PT&shopperResultUrl=https%3a%2f%2fsibs.docs.onlinepayments.pt%2ftutorials%2fserver-to-server&customParameters%5bSIBSMULTIBANCO_PtmntEntty%5d=23867&customParameters%5bSIBSMULTIBANCO_PtmntEntty%5d=2022-02-05T10%3a26%3a55.5555+00%3a00&customParameters%5bSIBSMULTIBANCO_RefLmtDtTm%5d=2022-02-05T10%3a26%3a55.5555+00%3a00

HTTP/1.1 400

Strict-Transport-Security: max-age=63072000; includeSubdomains; preload

X-Content-Type-Options: nosniff

X-XSS-Protection: 1; mode=block

Pragma: no-cache

X-Application-WAF-Action: allow

Vary: Accept-Encoding

Connection: close

Content-Length: 918

Cache-Control: private, no-cache, no-store

Content-Type: application/json;charset=UTF-8

Date: Sat, 05 Feb 2022 10:26:50 GMT

Set-Cookie: JSESSIONID=38CC426C38AA7338F183F495B167F7DF.uat01-vm-tx02; Path=/transaction; Secure; HttpOnly;Secure

Server: ACI

{"id":"8ac7a4a27ec4ee42017ec96c15783d24","paymentType":"PA","paymentBrand":"SIBS_MULTIBANCO","amount":"10.00","currency":"EUR","descriptor":"USAGE","merchantTransactionId":"ABC12345","result":{"code":"200.100.103","description":"invalid Request Message. The request contains structural errors"},"resultDetails":{"ExtendedDescription":"SIBSMULTIBANCO_RefIntlDtTm is missing or wrongly formatted","AcquirerResponse":"SIBSMULTIBANCO_RefIntlDtTm is missing or wrongly formatted"},"customer":{"givenName":"DOE","surname":"JOHN","ip":"213.58.172.221"},"billing":{"country":"PT"},"customParameters":{"SIBSMULTIBANCO_PtmntEntty":"23867,2022-02-05T10:26:55.5555 00:00","SIBSMULTIBANCO_RefLmtDtTm":"2022-02-05T10:26:55.5555 00:00"}

It would be problem of data type, make sure you are holding timezone value in text data type local variable.

Check the data type of Javascript output parameter, It should be text. 

FormatDateTime(CurrDateTime(),"yyyy-MM-ddThh:mm:ss.sss")+timezome

It is just concatenation of two string.

Correct. I ve tested your oml works fine but due to the API submission is urlencoded the plus sign is supresssed by the whitespace.

You have to pass, whole vlaue "2022-02-05T07:56:01.011+05:30" , how api will replace + sign with whitespace.

Please share your oml if possible.

I Will submit the file on the Next 8hours. Out of office

Simply by adding a string "%2B" for the urlencode to replace to + works

without your help with that function i wouldn't have done