# Encountering Error Message : The field Document Number must be a string with a minimum length of 1 and a maximum length of 16. - /einvoice/create\_einvoice

**URL:** <https://community.getswipe.in/t/encountering-error-message-the-field-document-number-must-be-a-string-with-a-minimum-length-of-1-and-a-maximum-length-of-16-einvoice-create-einvoice/876>\
**Category:** General\
**Created:** [September 18, 2024, 11:44am UTC](https://community.getswipe.in/t/encountering-error-message-the-field-document-number-must-be-a-string-with-a-minimum-length-of-1-and-a-maximum-length-of-16-einvoice-create-einvoice/876 "2024-09-18T11:44:20Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Vishnu\_diya](https://yyz1.discourse-cdn.com/flex003/user_avatar/community.getswipe.in/vishnu_diya/32/21_2.png) [@Vishnu\_diya](https://community.getswipe.in/u/Vishnu_diya)\
**Post date:** [September 18, 2024, 11:44am UTC](https://community.getswipe.in/t/encountering-error-message-the-field-document-number-must-be-a-string-with-a-minimum-length-of-1-and-a-maximum-length-of-16-einvoice-create-einvoice/876/1 "2024-09-18T11:44:20Z")

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It seems like the document number is not matching according to the E-invoice portal regular expression.

We request you to please change the invoice serial number according to the below instructions.  
​  
Must start with a letter or a digit between 1-9.  
Can contain up to 15 more characters (letters, numbers, hyphens, or slashes).  
Total length of invoice serial number is 1 minimum and 16 maximum characters.  
Cannot start with 0  
Cannot start with special characters like !, @, #, $, %, ^, &, \*, (, ), -, \_, =, +, {, }, [,], |, , :, ;, ", ', \<, \>, , ., ?, /