Hi,
nope, it's import limit. 
how many lines is in your file?
I recently imported (breaking by parts) 10-12 MB file with 50k records.
It seems like you are trying to put into Free base something much bigger than it can contain

Thanks! Kinda strange with such a low import limit but I guess there's a reason for it.

Hi there, I'm struggling with the same issue here,

I have a large excelsheet with 143K rows (and around 10 columns each), I can't add them neither thru CSV or .XLSX as in both cases the file exceeds the 5 MB limit...

Any workaround?

Hi,
the solution is the same - split by parts and load one by one
notice which part of your file less than 5 Mb, for example if your 143k rows file size is 14 Mb,
then 10k rows is ~1 Mb
copy-paste rows 1-39999 to file01.csv text file (create new file, set name, open with notepad)
then 40000-79999 to file02.csv etc..

I did that by hand, but then tried to make a script
unfortunately, when I tried to write script in VBA, it always produces error, record macro also screwed up, as you can't save selected cells. And Google sheets Script even worse in the terms of usability.
Another moment to praise Airtable scripting extension, which is a great sandbox to learn scripting.

Fortunately, I found an even simpler solution: this CMD script will split the CSV file into parts with a specified number of rows. All you need to do is substitute the required number of rows and your file name.

(Create new text file, paste script there, save as .CMD file, run)