Why do I get this message "Provided MIME type not permitted: application/vnd.ms-excel. Allowed types: text/plain, text/csv"

Question

URGENT: I have been uploading .csv files created in Excel to a company's website for YEARS and since the last flurry of updates (end of January to February 2026) I have received this full error message:

Sorry, there are error(s) and/or warning(s) relating to the upload.

Error at/with    The whole upload

DescriptionThere was a general error in processing the file. Further details: Provided MIME type not permitted: application/vnd.ms-excel. Allowed types: text/plain, text/csv

As a short term solution, I am having to complete the upload manually on the destination site. Not ideal as this could have errors in data transcription.

I tried to attach coppies of a successful and an unsuccessful one, but oddly, neither file was recognised!

Please bear in mind that I am a user not a programmer and need any solutions to be VERY simple for me to understand!

Answer 1

Hi,

Thank you for sharing your question. I understand that you are suddenly receiving an error message stating “Provided MIME type not permitted: application/vnd.ms-excel. Allowed types: text/plain, text/csv” when uploading a file that previously worked for years.

I know how urgent and frustrating this can be, especially when you are relying on these uploads for daily work and are now forced to enter information manually.

This issue usually appears when a website becomes stricter about the file’s MIME type after a recent platform update. Even though your file is saved as a .csv in Excel, Excel sometimes assigns the MIME type application/vnd.ms-excel instead of text/csv. When the company’s website only accepts text/csv, it will reject any file whose MIME type does not match, even if the file extension looks correct. The most helpful resolution is to open your file in Excel and explicitly use Save As, select CSV UTF‑8 (Comma delimited) to ensure the file is saved in the correct format, then upload it again. Another simple option is to open the CSV in a basic text editor and resave it so the system recognizes it as a true text/csv file. These steps usually correct the MIME type without needing any technical adjustments.

May I ask whether your version of Excel recently updated, or whether your company mentioned any changes to their upload rules during the January or February updates?

Please feel free to follow up with me if you want help checking your file type, saving it in the proper CSV format, or confirming that the website accepts the new upload. I’m here to help you get this working again smoothly.

 

I hope this helps.

 

Best Regards,

Noel

Answer 2

The error message you are encountering indicates that the MIME type of the file you are trying to upload is not permitted. Specifically, it mentions that the MIME type application/vnd.ms-excel is not allowed, and only text/plain and text/csv are permitted.

This issue often arises when Excel saves files in a format that is not recognized as a plain CSV file. Here are some steps you can take to resolve this issue:

1. Ensure Proper CSV Format: When saving your file in Excel, make sure to choose the correct format:
   • Go to File > Save As.
   • Select CSV (Comma delimited) (*.csv) from the file type dropdown menu.
   • Ensure that you are saving the file with UTF-8 encoding if the platform requires it.
2. Check for Additional Features: Make sure that the file does not contain any Excel-specific features such as formulas, multiple sheets, or special formatting, as these can cause the file to be saved in a different format.
3. Rename the File: Sometimes, simply renaming the file extension from .xls or .xlsx to .csv can help, but ensure you save it correctly as a CSV file in Excel first.
4. Open and Resave: Open the CSV file in a text editor (like Notepad) to confirm that it is in plain text format. If it looks correct, try resaving it again in Excel as a CSV file.
5. Upload Again: After ensuring the file is in the correct format, try uploading it again to the website.

If you continue to experience issues, consider reaching out to the website's support team for further assistance, as they may have specific requirements for file uploads.