I want to say the download failed since the file I was trying to download was very big and due to the slowness of our internet connection
Can I say the file was very heavy?
I want to say the download failed since the file I was trying to download was very big and due to the slowness of our internet connection
Can I say the file was very heavy?
"Very big" is perfectly fine. "Very big" or "very large" would be understood by just about any English speaker in that context. I would probably say "very large" myself.
"Heavy" is not a good choice; most people would probably understand it, but files are usually described using size words, not weight words.
Large digital files can be a problem for many reasons, but some explanations have different emphasis on different details. To start, we can make things simpler by saying
"I couldn't download the file because..."
This is a more common way to describe a problem like this, but still has a lot of meaning. It implies that there is a file you want to download, and it also says that there is something preventing you from downloading that file. So now we can complete the sentence in a few specific ways and see what they mean:
"I couldn't download the file because it was too large."
This sentence makes it clear that the size of the file is the problem. This means there is not enough free space on the computer. In this case, the speaker needs more disk space and faster internet would not help them.
"I couldn't download the file because my internet is too slow."
This sentence makes it clear that the slowness is the main problem. This means the speaker has enough space to store the file on their computer, but the internet connection is too slow to download the file in a reasonable amount of time. This can be a common problem for people trying to download large files (sound, video, programs, etc.) over a 56k connection or similar, but if the listener knows the file is rather small (a picture, word document, etc.) then they might find this excuse hard to believe.
"I couldn't download the file because the file was big and my internet is too slow."
This sentence is similar in meaning to the previous sentence, but adding "the file was big" helps to remind the listener that the file is not a trivially small file. If you say "too big" AND "too slow" this COULD mean that both problems occur, but most listeners would assume it is just the slow connection that is the main problem.
"I couldn't download the file because the file was too big for my monthly limit."
This is maybe more uncommon, but would specifically apply to internet-connected telephones (in that case it is usually called "data plan") or some internet connections where the amount of data available in a month is limited. This sentence explains that you probably can download the file (you have enough space and a fast enough internet connection) but you are prevented from doing so because you don't want to pay extra fees for downloading a such a large file, or possibly your internet provider will stop sending data after you pass that limit.
Words like "heavy" are not in common usage for describing files. It is sometimes used to describe internet usage (people who download a lot are considered "heavy users") but this "heavy" feeling is never associated with the file itself.
You could say "the download failed because the low speed of the internet connection could not support the large file size."
Also
The download failed due to poor internet connectivity. It could no longer support the large file size.
I would say that the file "takes up a lot of (memory) space." Which is why it is hard to load at one "sitting."