We are on the free plan of Slack. This means, that we've 5 GB of space for files.
Workspaces on Slack’s Free plan have a total of 5GB of file storage to
share. If you’ve reached the limit, files will remain accessible in
Slack but you won't be able to upload any more. You can delete shared
files to make room for new ones or upgrade to a paid plan.
As we hit the zenith, Slack started to send messages along the uploaded attachments:
Your file was uploaded — it’s safe and sound in Slack. Unfortunately
your workspace doesn’t have any storage space left. To get more space,
you can upgrade to a paid account or delete some of your older files.
What does that mean? This warning is quite confusing. Does it mean we have unlimited space, but it's not guaranteed to last for an eternity? Does it mean older files get deleted to make room for the newly added file? Is it just a temporary thing and sooner or later we really aren't able to upload files anymore?
Best Answer
Slack's documentation says-- Workspaces on Slack’s Free plan have a total of 5GB of file storage to share. If you’ve reached the limit, files will remain accessible in Slack but you won't be able to upload any more...
But as you and I have experienced, it doesn't prevent you from uploading and doesn't prevent team members from retrieving the file. Update: It looks like some files that are uploaded beyond the limit are disappearing from threads and the files panel within 24hrs of upload, leaving only the warning message.
(My guess is that these over-limit files stick around as long as slack users are interacting with them, and eventually time out— becoming unavailable when left alone.)
This is probably Slack's way of not letting it's application become a speed bump for Workspaces.
Importantly, a file upload does count as another message, which causes the 10,000 message limit to come into play. A serious drawback here (that may cause some teams to buy Slack) is not being able to contextually find information by searching through conversations. When trying to find keywords in old conversations, users will meet the 10k limit warning which reads "There's more to this conversation..." paywall.
Source: https://get.slack.help/hc/en-us/articles/115002422943-Message-and-storage-limits-on-the-Free-plan#file-storage-limit