Direct answer
For the Samsung Galaxy S20 family, large media, downloads, app caches and system-update reserve should be measured before deletion. First, open storage settings and identify the largest verified categories.
What this covers
- Samsung Galaxy S20 family (SM-G980/SM-G981/SM-G985/SM-G986*)
- Current Galaxy family; confirm the complete SM identifier, region and One UI version before repair or firmware instructions.
- The specific fault this record addresses: storage is full or the device cannot install updates
What it does not cover
- ×The same symptom on a different Samsung product line, which has its own record and its own cited source
- ×An on-screen error code whose meaning has not been checked against this exact model's manual
- ×Live electrical, gas, sealed-system, internal battery-cell or structural repair — a technician boundary, not a self-service step
Differential
What actually causes this, and how to tell them apart
These are ordered by how often each one is the answer, not by how easy it is to try. The point of the middle column is that two causes producing the same headline symptom rarely produce the same detail — that detail is what tells you which one you have before you change anything.
- 1
Photos and video, almost always
What separates it The storage breakdown shows photos far above everything else. Video in particular is enormous, and high-resolution or high-frame-rate recording multiplies it.
How to confirm Open the storage breakdown and read the largest category. This names the cause in one look on most phones.
- 2
Deleted items still in a recently-deleted album
What separates it Deleting photos frees nothing. Both platforms retain deleted media for a period so it can be recovered.
How to confirm Empty the recently-deleted album explicitly. This is the most common reason deleting does not help, and it surprises people every time.
- 3
One app's cache has grown enormous
What separates it A streaming, mapping, social or messaging app is far larger than the app itself should be. Downloaded media and offline maps accumulate silently.
How to confirm Sort apps by size in the storage breakdown. Offline content is the usual answer and it is often forgotten rather than wanted.
- 4
Messaging attachments
What separates it A messaging app is one of the largest items. Years of photos and videos received in group chats are stored locally and never reviewed.
How to confirm Look inside the app's own storage management. This is frequently the single biggest recoverable block on the phone.
- 5
An update needs far more free space than its own size
What separates it An update refuses to install with more free space than the update appears to need. Installation requires room to unpack and stage as well as to store.
How to confirm Free substantially more than the stated size. This is normal and not a sign of anything wrong.
- 6
The system or 'other' category
What separates it A large block attributed to system with no files behind it. Much of this is caches the phone releases automatically under pressure.
How to confirm Restart the phone and give it time. Chasing this category directly is largely futile and some methods for doing so are actively harmful.
- 7
Cloud settings that keep full-resolution copies locally
What separates it Storage is full despite everything being backed up. Keeping originals on the device is a setting, and optimised storage is the alternative.
How to confirm Check whether the photo library is set to optimise device storage or to keep originals.
- 8
Downloads and files nobody remembers
What separates it A large downloads folder or offline files from apps that were used once.
How to confirm Review the files area rather than only the apps list.
Before you touch a setting
Record this first — changing settings destroys the evidence
Every item below stops existing the moment a reset, re-pair or settings change is made. Written down first, they are what separates the causes above; recovered afterwards, they are guesswork.
- The storage breakdown by category, photographed before deleting anything, so the effect of each action can be judged.
- How much free space there is now, and how much the failing operation says it needs.
- Whether the recently-deleted album has been emptied.
- The largest three apps by size, and whether their size is app data or downloaded content.
- Whether the photo library is set to optimise device storage or to keep full-resolution originals.
- Whether everything important is actually backed up before anything is deleted.
Read the storage breakdown before deleting anything
ReversibleThe phone already categorises what is using space, and on most phones the largest category names the cause in one look. Deleting at random first wastes effort on the small categories and makes it impossible to judge what helped.
Confirm what matters is backed up
ReversibleEvery step below removes something. A backup verified before you start is what makes the difference between freeing space and losing photos, and 'it should be syncing' is not the same as checking.
Empty the recently-deleted album
Reset / data riskBoth platforms retain deleted media for a period so it can be recovered, which means deleting photos frees nothing until this is emptied. This is the most common reason deleting appears not to work at all.
Sort apps by size and look at what is inside the largest
ReversibleA streaming, mapping, social or messaging app that is far bigger than the app should be is holding downloaded content — offline maps, cached video, years of chat attachments. That is usually the largest single recoverable block on the phone.
Use each app's own storage management where it has one
ReversibleMessaging apps in particular offer a view of attachments by size and age, which is far more precise than deleting the app. It also keeps your history, which clearing the app's data would not.
Switch the photo library to optimised storage
ReversibleWhere everything is backed up, keeping full-resolution originals on the device is a choice rather than a requirement. Optimised storage keeps a smaller copy locally and fetches the original when needed, and it is usually the largest single change available.
Free substantially more than the update says it needs
ReversibleInstallation requires room to unpack and stage as well as to store, so an update commonly needs several times its own size. This is normal, and it is why an update refuses with what looks like enough space.
Leave the system category alone
ReversibleMuch of it is caches the phone releases automatically under pressure. Chasing it directly is largely futile, and the third-party tools that claim to clear it are at best useless. A restart and some time is the correct response.
Re-read the breakdown after each change
ReversibleThis is how you learn which action actually recovered space, rather than doing five things and crediting the last one. It also stops you deleting things that were never the problem.
Model-specific
What is true of this model and not of its siblings
Generic advice for the product line fails here. Each item below is a property of this specific model family that changes which of the steps above apply to you.
- Model scope
- SM-G980/SM-G981/SM-G985/SM-G986*. Current Galaxy family; confirm the complete SM identifier, region and One UI version before repair or firmware instructions.
- Tier — flagship base (no S Pen)
- The compact 2020 flagship, no S Pen. One UI over Android, an older device near/past its major-update window.
- eSIM + physical SIM, IP68
- eSIM and physical SIM, IP68, fast + wireless charging.
- Age
- Battery ageing and reduced updates are age factors, not faults.
- Symptom boundary
- This record covers Samsung Galaxy S20 family when it storage is full or the device cannot install updates. A different symptom on the same hardware, or this symptom on a different Samsung product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
Continuing past any one of these costs more than the repair saves — in safety, in warranty, or in evidence a technician needs.
- !Storage reports as full with the breakdown accounting for far less than the capacity, after a restart and time — that can be a filesystem problem.
- !The phone will not free space no matter what is deleted, which sometimes indicates a stuck process holding files open.
- !There is no backup and the only way forward involves deleting something irreplaceable.
- !The device has no expandable storage and its capacity is genuinely inadequate for how it is used, which is a hardware decision rather than a cleanup.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Where the manufacturer's article stops. Samsung publishes this as "Low storage space error appears on Samsung phone or tablet". Covers the low-storage error that blocks updates and app installs on a Galaxy phone, and how to free space. Probed 2026-08-21: title-verified. What that article does not carry is the model boundary — it is written for a product line, and SM-G980/SM-G981/SM-G985/SM-G986* is the scope applied here. Where a control label, terminal, indicator pattern or reset sequence differs on your unit, the manual for that exact model is the authority, not this page and not the article.
Exact questions
Common follow-ups
My Galaxy S20 is getting slow and the battery is weak.+
Both are age-related on a 2020 flagship: the battery has lost capacity, and a nearly full phone plus years of app updates slow it down. Free storage, disable always-on display, reduce background apps, and update what software is still available. A battery replacement helps runtime. It is also near the end of its major-update support, so some newest features simply will not arrive — that is support age, not a fault.
I deleted photos and nothing changed.+
Empty the recently-deleted album. Both platforms retain deleted media for a period so it can be recovered, which means deleting frees nothing at all until that album is emptied. This surprises people every single time.
What is the 'system' or 'other' storage?+
Mostly caches, logs and staging space that the phone releases automatically when it genuinely needs to. Chasing it directly is largely futile, and the third-party apps that claim to clear it do not have the access they would need to. Restart and give it time.
Where should I look first?+
The storage breakdown by category. On most phones photos and video are far above everything else, and video in particular is enormous. The breakdown names the cause in one look, where deleting at random wastes effort on the small categories.
One app is using far more space than it should.+
It is holding downloaded content — offline maps, cached video, or years of chat attachments. Use that app's own storage management rather than deleting the app: it is more precise and it keeps your history.
An update says I need more space than I have, but I have more than the update size.+
Installation needs room to unpack and stage as well as to store the result, so it commonly requires several times the stated size. That is normal behaviour and not a sign of anything wrong — free more than you think you need.
Everything is backed up to the cloud but the phone is still full.+
Check whether the photo library is set to keep full-resolution originals on the device. Backed up and stored locally are different things, and switching to optimised storage is usually the single largest change available on a full phone.
Are cleaner apps worth installing?+
No. They do not have the access they would need to clear the categories they claim to, they occupy storage themselves, and several are adware. The phone's own storage breakdown does the useful part and does it accurately.
My phone is slow because it is full.+
That is real — a phone with almost no free space has nowhere to write temporary files, and everything suffers. Getting back to a comfortable margin rather than scraping a few hundred megabytes is what actually fixes it.
Does this answer apply to every Samsung model?+
No. It is scoped to SM-G980/SM-G981/SM-G985/SM-G986*. Current Galaxy family; confirm the complete SM identifier, region and One UI version before repair or firmware instructions.
What should I record before troubleshooting storage full or not enough space?+
Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.
Why is a factory reset not the first step?+
A reset can erase accounts, networks, maps, schedules or preferences without distinguishing storage full, not enough space. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Never erase photos, messages, authenticators or work files without a verified second copy.
Answer for the exact device and software version shown above.