“Gemini 3.1 Pro is not available on this version. Please upgrade to the latest version.” message: What it really means, Why it happens, and How users fix it

This error looks like a model failure, but it behaves like a client problem.

It shows up most when a tool tries to select Gemini 3.1 Pro and the local build cannot support that selection.

That mismatch creates a frustrating experience because the interface suggests the model exists while execution fails immediately.

The pattern is strongest inside Google Antigravity and the tools that integrate with it, rather than inside the consumer Gemini app.

People hit it when they are trying to do real work, like coding, agent tasks, or document workflows, not casual chat.

The reason it spreads fast is that it appears during rollout windows where server-side changes move faster than local client updates.

The result is a “half-updated” environment where menus, flags, and manifests disagree with each other.

If you treat it as a network glitch, you waste time.

If you treat it as version gating, you can solve it deterministically.

The useful part is that the community has already converged on a small set of fixes that actually work.

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Where this error actually appears in the wild, and why it is more diagnostic than generic “Something went wrong.” messages.

The most consistent location is Google Antigravity, including Antigravity-based IDE and agent workflows.

The same exact string is also reported through integrations that wrap Antigravity, such as plugins and authentication helpers, because they inherit the same compatibility layer.

This is why the message feels “official,” because it is often produced by an official client, but it can also be triggered through third-party wrappers.

It is reported less often on the consumer Gemini app or web experience, where errors are typically more generic and less version-specific.

That difference matters because the Antigravity ecosystem is more sensitive to model-selection manifests and schema versions.

When Antigravity cannot map a model identifier to a supported configuration in that build, it fails loudly with this exact message.

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Where users most often see the error, and what that implies.

Surface	How the error typically appears	What it implies
Google Antigravity	The exact quoted error string appears when selecting Gemini 3.1 Pro	Client build does not support the model selection mapping
Antigravity integrations and wrappers	The same string appears inside plugins or authentication layers	The wrapper inherits the same version gating and schema constraints
Gemini consumer app or web	Usually generic failure messages rather than this specific string	Consumer surfaces mask version gating behind simpler error handling

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What the message means technically, and why it is not the model failing.

This error is a version-gating signal, not a statement about Gemini 3.1 Pro quality or uptime.

The client is requesting or selecting a model that the local build cannot support under its current manifest or schema.

That can happen when the UI exposes a new option before the underlying client components are aligned.

It can also happen when the rollout is split, so a user is eligible to see the option but not eligible to execute it on that exact OS and build.

The practical effect is that the model looks selectable, but the request fails because the client cannot complete the compatibility handshake.

This is why the fix is almost never “try again later” and almost always “update the client in a way that actually changes the build.”

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What is happening under the hood when the error appears.

Layer	What is happening	Why it produces this exact message
Client manifest and model mapping	The build does not contain the correct mapping for gemini-3.1-pro	The client rejects the selection as unsupported in this version
Feature flags and staged rollout	Flags expose the model option, but execution is not enabled for that build	The UI and execution layer disagree, creating a “half-updated” state
Local schema and bridge components	An outdated schema still drives the request path	The client identifies the request as incompatible and blocks it

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Why Windows shows up as the loudest failure case, and how auto-updaters create “latest-but-not-latest” confusion.

A recurring theme is that users believe they are on the latest version because they do not see an update mechanism.

Some users report there is no obvious “Check updates” control, which turns updating into guesswork.

Windows adds a specific failure mode where the auto-updater can be out of sync, so the client stops receiving the build that would fix the manifest mismatch.

In that scenario, the user is effectively pinned to a build that looks normal but cannot execute the new model selection.

This explains why the error can be “mass,” because many users can be stuck on the same stale build during the rollout window.

It also explains why manual reinstall becomes the dominant fix, because it bypasses the failing update path and refreshes the full client package.

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Why the update path breaks, and what it looks like to the user.

Failure mode	What the user experiences	Why it drives this error
Missing or unclear update control	No visible way to update inside the client	Users remain on an incompatible build
Auto-updater misalignment on Windows	The client behaves as if it is current	The needed build never arrives, so compatibility never updates
Split rollout timing	Some accounts see 3.1 Pro before the client can execute it	Users hit version gating even after “updating”

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Which builds are repeatedly mentioned in reports, and why version strings matter more than impressions.

Users report specific build strings often enough that they function like a fingerprint for the problem window.

A common stable rollback point is 1.16.5-1770081357, used when newer versions introduce UI regressions.

A commonly discussed upgrade window includes 1.18.3-1771473975, which appears during the period where 3.1 Pro adoption accelerates.

Another commonly mentioned build is 1.18.4-1771638098, which is associated with manual update targeting and also appears in threads discussing instability.

The important point is not that one number is “good” and another is “bad,” but that mismatched versions correlate strongly with this gating message.

So the fastest diagnostic step is always to capture the full version string, not only the major.minor label.

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Build versions frequently mentioned in user reports and how they are used in practice.

Build	How it is used by users	Why it matters for this error
1.16.5-1770081357	Rollback target for stability	Often used when newer builds regress, but may lack 3.1 Pro mapping
1.18.3-1771473975	Upgrade window build in many threads	Appears around the period of 3.1 Pro rollout behavior
1.18.4-1771638098	Manual update target in Windows discussions	Appears in threads about fixing gating and also about instability

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Why the “Gemini 3 Pro is no longer available” message often appears next, creating the worst kind of limbo.

A frequent companion issue is a message telling the user that Gemini 3 Pro is no longer available and they must switch to 3.1 Pro.

Then the user switches to 3.1 Pro and immediately gets the “not available on this version” gating message.

That pairing creates a true dead-end because the old model path is being deprecated while the new model path is version-gated.

The most plausible operational explanation is that server-side deprecation messaging moves faster than client-side compatibility updates.

So the client is pushed away from 3 Pro before it is fully ready to execute 3.1 Pro.

This is why users describe it as being stuck in limbo, because both exits are blocked by different layers of the system.

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The common “limbo” pattern and what it usually indicates.

Step	What the user sees	What it usually indicates
First message	Gemini 3 Pro is no longer available, switch to 3.1 Pro	Server-side deprecation has reached that account or pathway
Second message	3.1 Pro is not available on this version, upgrade required	Client-side build is not aligned to execute 3.1 Pro
Result	No usable Pro model path	Rollout timing and client schema mismatch

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What fixes are actually confirmed in user reports, and why they work when simpler attempts fail.

The most commonly repeated fix is a manual reinstall or manual upgrade from the official Antigravity installer source.

This works because it refreshes the entire client package, including the manifest and any bridge components the auto-updater may have missed.

On Windows, users repeatedly report success using winget upgrade for Antigravity, and in stubborn cases a forced reinstall through winget.

This works because it bypasses broken updater state and pulls a fresh package consistent with the newest published channel.

Some users report a plain rollout delay even after updating, which implies that client update is necessary but not always sufficient if eligibility flags have not propagated.

A smaller set of reports mention a workaround where starting with a different model like Flash triggers a refresh that makes 3.1 Pro usable afterward.

That workaround is anecdotal, but it appears in real user narratives and matches the idea of a cached configuration that can be refreshed by switching modes.

Downgrade is used mostly to escape UI regressions, not as a primary fix for the gating message, but it becomes part of the real-world toolkit when stability is the priority.

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Fixes users report as working, mapped to the technical reason they help.

Fix	What users do	Why it helps
Manual reinstall from official installer	Download and reinstall over the existing installation	Forces a full package refresh and updates manifests
Windows winget upgrade	Run a winget upgrade for Antigravity	Bypasses stuck auto-updater paths and pulls the current build
Windows winget force install	Force reinstall via winget when upgrade fails	Resets local state and overwrites stale components
Rollout delay acceptance	Update and then wait for enablement	Flags can propagate after the client is already updated
Flash-first refresh workaround	Start with Flash, then reselect 3.1 Pro	May refresh cached configs and reinitialize model mapping
Temporary downgrade for regressions	Roll back for stability, then upgrade when needed	Keeps the client usable when newer builds freeze or lag

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Which “nearby” issues are often confused with this error, and how to tell them apart quickly.

A separate class of failures involves Antigravity server crashes at startup.

Another class involves UI freezes or extreme lag, reported especially on some Linux setups, which can look like “the model is broken” when it is actually the client.

Some users report abnormal output behavior such as leaked internal thought blocks or loop-like responses, which suggests the model is running but producing unstable behavior.

Some users report quota-related lockouts that look like model unavailability but are actually usage limits.

These issues cluster in the same time window, so people lump them together as “3.1 Pro problems,” even though the root causes are different.

The diagnostic trick is to treat the exact quoted error string as one specific class of issue, and everything else as a different class until proven otherwise.

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Commonly conflated issues and why they are not the same as version gating.

Issue category	What it looks like	Why it is different
Server crash at launch	Server crashed unexpectedly, app fails to start	Not a model selection gating issue
UI freeze or lag	The app becomes unresponsive during runs	Performance regression, not compatibility gating
Abnormal output behavior	Odd loops or leaked internal blocks	The model is executing, but behavior is unstable
Quota lockout	Model quota reached on a paying account	Availability is blocked by limits, not version

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What to check to diagnose your exact case deterministically, without guessing.

First, capture the full Antigravity version string including the build ID.

Second, identify the OS, because Windows update-path issues are a repeated pattern.

Third, identify how the client was installed, because the update path differs across installer, winget, and distro packages.

Fourth, confirm whether any wrapper or plugin is involved, because wrappers can be incompatible even when the base client is updated.

Fifth, confirm whether the contradictory “3 Pro is no longer available” message appears, because that indicates the classic limbo case.

If you log those five items, you can map your case to a known pattern quickly.

Then the right fix becomes a mechanical choice, not a trial-and-error ritual.

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Deterministic checklist for narrowing the root cause.

Check	What to record	What it tells you
Antigravity build	Full version plus build ID	Whether the client is version-gated
Operating system	Windows, Linux, macOS	Whether updater issues are likely
Install method	Installer, winget, distro package	Whether update paths can be bypassed
Wrappers or plugins	Any non-official integration layer	Whether incompatibility can persist after updating
Limbo symptoms	3 Pro deprecation message plus 3.1 Pro gating message	Whether you are in split-rollout dead-end

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