"finishReason": "SAFETY" | "RECITATION" | "OTHER" | "PROHIBITED_CONTENT" | "SPII"
Gemini’s FinishReason enum has twenty-two values. For eleven of them, the documentation is one row of one enum, and that row explains the value using the value’s own name. SAFETY means the content was flagged for safety reasons. RECITATION means it was flagged for recitation reasons. OTHER means “Unknown reason.” Reading the row tells you what you already knew from the identifier. This page quotes all eleven rows, names exactly what each one withholds, and then does the only thing left to do: separate them using the rest of the response object, which is documented even where the enum is not.
In ten seconds. Do not start at finishReason. Start at promptFeedback.blockReason, because five of these names exist in two different enums and mean different things in each: if blockReason is set, your prompt was rejected and no candidate was ever generated. Only if it is absent do you read candidates[0].finishReason, and then, on the same candidate, finishMessage, safetyRatings and citationMetadata — the only three fields in the object that carry anything about why it stopped.
And the honest part: that procedure does not finish the job, and this page says so rather than pretending. It cleanly separates the prompt-side block from the candidate-side stop, and it cleanly identifies SAFETY and RECITATION. For the remaining values — PROHIBITED_CONTENT, SPII, BLOCKLIST, LANGUAGE, the four IMAGE_ values and MALFORMED_RESPONSE — no field described in the five files we read tells you anything the value’s own name did not. That is the finding, not a gap in our reading, and the count that supports it is at the bottom of the page.
Calling documentation circular is an accusation, so here is the test, and it is our test, not Google’s: a row is circular if the explanatory sentence contains the value’s own name, or a direct synonym of it, and adds no referent you could look up — no category list, no field to inspect, no second document. By that test the eleven rows below fall into three kinds, and the kind matters because it changes what you can do next:
Two values that look like they belong here do not, and are handled further down rather than hidden: BLOCKLIST, whose row introduces a genuinely new noun and so fails our test, and LANGUAGE, which is partly rescued by a sentence in a different file. Two more belong by the same test and are easy to miss because they sit at the far end of the enum, past the values that have pages of their own: IMAGE_OTHER and MALFORMED_RESPONSE.
All of these come from the Gemini API reference for generateContent, from the FinishReason enum, which is introduced with one line:
Defines the reason why the model stopped generating tokens.
And then the rows. Each quote below is the complete documentation for that value in that file — not an excerpt of a longer section, because there is no longer section.
SAFETY The response candidate content was flagged for safety reasons.
RECITATION The response candidate content was flagged for recitation reasons.
LANGUAGE The response candidate content was flagged for using an unsupported language.
OTHER Unknown reason.
PROHIBITED_CONTENT Token generation stopped for potentially containing prohibited content.
SPII Token generation stopped because the content potentially contains Sensitive Personally Identifiable Information (SPII).
IMAGE_SAFETY Token generation stopped because generated images contain safety violations.
IMAGE_PROHIBITED_CONTENT Image generation stopped because generated images has other prohibited content.
IMAGE_OTHER Image generation stopped because of other miscellaneous issue.
IMAGE_RECITATION Image generation stopped due to recitation.
MALFORMED_RESPONSE Finished due to malformed response.
Three details in that block are worth naming, because they are the kind of thing a reader assumes is a transcription error on our part. The IMAGE_PROHIBITED_CONTENT row reads “generated images has other prohibited content” — the disagreement is Google’s, quoted as published, and so is the word “other” in it, which has no antecedent in the row and only makes sense if you read the row above it. IMAGE_SAFETY is filed under token generation while the three rows around it are filed under image generation, in the same enum, for the same subject. And SPII is the one row whose sentence is longer than its identifier for a reason: it is the only expansion in the family.
This is the single most useful thing on this page, and it is fully documented. The same file that defines FinishReason also defines a second, smaller enum called BlockReason, and five names appear in both. The reference states the division in three bullets:
Returns either all requested candidates or none of them Returns no candidates at all only if there was something wrong with the prompt (check promptFeedback) Reports feedback on each candidate in finishReason and safetyRatings.
And on the field itself:
Optional. If set, the prompt was blocked and no candidates are returned. Rephrase the prompt.
So the order of reading is fixed by the documentation, not by us: if promptFeedback.blockReason is set there is no candidate to inspect, and a finishReason you think you are looking at is not there. Here is the second enum in full, so the overlap is visible rather than asserted:
Specifies the reason why the prompt was blocked.
BLOCK_REASON_UNSPECIFIED Default value. This value is unused.
SAFETY Prompt was blocked due to safety reasons. Inspect safetyRatings to understand which safety category blocked it.
OTHER Prompt was blocked due to unknown reasons.
BLOCKLIST Prompt was blocked due to the terms which are included from the terminology blocklist.
PROHIBITED_CONTENT Prompt was blocked due to prohibited content.
IMAGE_SAFETY Candidates blocked due to unsafe image generation content.
Five collisions: SAFETY, OTHER, BLOCKLIST, PROHIBITED_CONTENT and IMAGE_SAFETY are each a valid value of two different enums on two different fields. A log line that records the string without the field name is ambiguous, and a handler that switches on the string alone will treat a rejected prompt as a truncated answer. That inference is ours; the two enums it rests on are quoted above in full.
The BlockReason rows are also, quietly, better written than their FinishReason twins. The prompt-side SAFETY row tells you which field to inspect next. The candidate-side one does not. Same word, same product, same file, one of them actionable.
The safety-settings guide is the only one of the five files we read that explains how to get a reason out of a response. It is worth quoting at length because it is the whole of the procedure:
generateContent returns a GenerateContentResponse which includes safety feedback. Prompt feedback is included in promptFeedback. If promptFeedback.blockReason is set, then the content of the prompt was blocked. Response candidate feedback is included in Candidate.finishReason and Candidate.safetyRatings. If response content was blocked and the finishReason was SAFETY, you can inspect safetyRatings for more details. The content that was blocked is not returned.
Four things follow, and only the fourth is ours. First, safetyRatings is populated per category, and the reference says there is at most one rating per category — so a SAFETY stop can be resolved to a category, which makes it the best-instrumented value on this page. Second, the instruction is scoped, in Google’s own sentence, to finishReason being SAFETY; it is not offered for PROHIBITED_CONTENT, for SPII, or for any IMAGE_ value. Third, the last sentence settles a question the enum never addresses: the blocked content is not returned, so an empty content beside a set finishReason is expected rather than a bug in your parser. Fourth, our reasoning, not Google’s: because that guide names only one of the eleven values, safetyRatings cannot be used to tell PROHIBITED_CONTENT from SPII from BLOCKLIST — it is not documented to carry a category for them, and we did not test whether it does.
The measured version of that claim: in the 122,408 bytes of the safety-settings guide, SAFETY appears once, and PROHIBITED_CONTENT, SPII, BLOCKLIST, RECITATION, LANGUAGE, IMAGE_SAFETY and the other IMAGE_ values each appear zero times. The document that configures the content filters names exactly one of the stop values those filters produce.
This is the one real rescue in the whole family, and it is not in the enum. The Candidate object has a field whose description does what the RECITATION row refuses to do:
Output only. Citation information for model-generated candidate.This field may be populated with recitation information for any text included in the content. These are passages that are “recited” from copyrighted material in the foundational LLM’s training data.
(The missing space in “candidate.This” is in the published file; we have not corrected it.) That is the only place in the five files we read where the word is given a meaning: recitation is reproduction of copyrighted material from training data. So finishReason: RECITATION has both a definition and a field to read, and the definition lives two screens above the row that needed it.
The troubleshooting page adds the only remedy offered for any value on this page:
If you see the model stops generating output due to the RECITATION reason, this means the model output may resemble certain data. To fix this, try to make prompt / context as unique as possible and use a higher temperature.
Note what that sentence does: it weakens the definition. The reference says copyrighted material from training data; the troubleshooting page says the output may resemble certain data, which is not the same claim. We report both rather than choosing, because both are published and we have no way to reconcile them from the bytes we hold.
The last field in the Candidate object is the one that should end this page, and here is everything the reference says about it:
Optional. Output only. Details the reason why the model stopped generating tokens. This is populated only when finishReason is set.
Read it twice. It promises details, it promises population whenever a reason is set, and it specifies nothing about the contents — no format, no enumeration, no example anywhere in the file. finishMessage appears twice in the 1,232,462 bytes of the reference, both times in the Candidate object — once in the field list and once in the JSON representation — and zero times in the other four files. Our recommendation, not Google’s: log it unconditionally beside finishReason, because it is the only documented channel by which any of these eleven values could ever carry a detail, and you cannot discover what it holds for SPII or IMAGE_OTHER from any document we could read — only from your own traffic.
By our own test BLOCKLIST is not circular. Its FinishReason row introduces a new noun instead of reusing the identifier, which nine of the eleven rows above do not manage:
BLOCKLIST Token generation stopped because the content contains forbidden terms.
It is here because of what happens next. Its twin in the other enum — BLOCKLIST Prompt was blocked due to the terms which are included from the terminology blocklist, quoted in full above — is circular, by repetition, and it is the only place in all five files where the thing is named. The phrase appears once across the 2,729,724 bytes of the five files; lowercased, the word appears that same once, inside that phrase, and the uppercase enum name appears twice — both of those in the two rows quoted on this page, and nowhere else. No file we read says whose blocklist it is, where it is configured, whether it is Google’s or the project’s, or how to see its contents; the safety-settings guide, which is where a reader would look, contains the string zero times. So BLOCKLIST fails the circularity test on one row, passes it on the other, and is in practice the least actionable value in the family. Dropping it from the table and then saying nothing about it would have been the wrong kind of tidy.
The LANGUAGE row is circular by repetition: an unsupported language. The troubleshooting page, under Known issues, gets closer than any other sentence in the five files:
The API supports only a number of select languages. Submitting prompts in unsupported languages can produce unexpected or even blocked responses. See available languages for updates.
That tells you the restriction is real and that it applies to the prompt, which the enum row does not say. What it does not do is name one language. Across all five files the string supported languages appears exactly once, and it is inside the word unsupported languages in the sentence just quoted; the list itself is behind a link, which we deliberately did not follow, because this page was built with no network requests at all. So the honest state of LANGUAGE is: documented to exist, documented to be about your input, and not resolvable to a language from anything on our disk.
After all four steps, the eleven values — and BLOCKLIST, taken with them — sort into three groups. This sorting is ours; every sentence it rests on is quoted above.
That is a weaker result than the page’s title promises, and it is the result. The useful version of this page is not a decoder ring; it is three facts: read promptFeedback.blockReason before finishReason or you will misread five values; log finishMessage because nothing else can carry a detail; and for six of the eleven, stop looking for a cause in the documentation, because in the five files we read there isn’t one.
ESCALATION — “Request was filtered by an escalation rule” — introduces a mechanism rather than repeating itself, so it fails our test, and it is arguably worse documented than anything above: the string appears once in the reference and zero times in the other four files, and no file we read says what an escalation rule is. NO_IMAGE — the model was expected to generate an image, but none was generated — is simply not circular; it states a condition you can check. Both are in the same enum and neither fits the family, so neither is in the table.
Every sentence inside a quote block above was read out of a copy of the document it is attributed to that was already stored in this lab’s repository before this page was written. Nothing was fetched to write this page — not one request left the machine — and nothing here is quoted from memory. The copies, with the byte count of the file actually read:
The reference page and the safety-settings page each carry the same licence line: “Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License”. Each of the eleven values above was searched for in all five files. Nine of them appear in the reference and nowhere else: LANGUAGE, PROHIBITED_CONTENT, SPII, IMAGE_SAFETY, IMAGE_PROHIBITED_CONTENT, IMAGE_OTHER, IMAGE_RECITATION, MALFORMED_RESPONSE and BLOCKLIST are each zero in the thinking guide, zero in the function-calling guide, zero in the troubleshooting page and zero in the safety-settings guide. Two appear outside it, once each: RECITATION once in the troubleshooting page, and OTHER once there too — both quoted above. SAFETY appears once in the safety-settings guide and zero times in the other three guides. In the reference itself the counts are: SAFETY 2, OTHER 2, PROHIBITED_CONTENT 2, BLOCKLIST 2, IMAGE_SAFETY 2, SPII 2, and RECITATION, LANGUAGE, IMAGE_PROHIBITED_CONTENT, IMAGE_OTHER, IMAGE_RECITATION and MALFORMED_RESPONSE 1 each — and every one of the twos is the value appearing in both enums, except SPII, whose two are the acronym and its expansion inside the same single row. finishReason appears 6 times in the reference, 2 in the safety-settings guide, and zero times in the thinking guide, the function-calling guide and the troubleshooting page. finishMessage: 2 in the reference, zero in the other four. citationMetadata: 2 in the reference, zero in the other four. BlockReason: 3 in the reference, zero in the other four — while BlockedReason, the spelling the troubleshooting page uses, appears once there and zero times in the reference. The phrase terminology blocklist appears once in all five files combined; lowercased blocklist appears that same once, inside that phrase, while the uppercase enum name BLOCKLIST appears twice, both in the reference and both quoted on this page. The string supported languages appears once across all five files, and that once is inside the word unsupported languages in the troubleshooting sentence quoted above — there is no list of supported languages in any of the five files, only a link out of one of them, which we did not follow.
Those counts are the evidence for every claim of silence on this page; they were produced by searching the five files named above and nothing else, after stripping tags and collapsing whitespace, and counting only whole-token matches — so the two occurrences of SAFETY in the reference do not include the two of IMAGE_SAFETY, which are counted separately. We did not read the SDK source for any language, and nothing above describes it. We did not follow a single link out of these five files, including the one the troubleshooting page offers for its list of languages. A claim on this page about what Google does not say is a claim about these five files on the date they were fetched, and is not a claim about every document Google has published. Where this page reasons past the documentation it says so in the sentence that does it.
There is a written guide: the full finishReason and BlockReason dispatch as one table you can hold against your own response handler, including the five names that appear in both enums and the log line that records which field they came off, so an ambiguous value is never written down ambiguously.
No page on this site has a checkout widget of its own. There is a written guide behind this host and it is on sale at $19 on a storefront that delivers the files automatically and carries a 30-day money-back guarantee: buy it there; the guide can also be paid for with 19 USDC on Base at the payment page, where delivery is by hand as a reply to your email. Every page on this site, including this one, is free to read in full, with no sign-up and nothing gated.
The short version: eleven of Gemini’s twenty-two finishReason values are documented by one enum row that explains the value with the value’s own name — SAFETY, RECITATION, LANGUAGE, OTHER, PROHIBITED_CONTENT, SPII, IMAGE_SAFETY, IMAGE_PROHIBITED_CONTENT, IMAGE_OTHER, IMAGE_RECITATION and MALFORMED_RESPONSE, all eleven rows quoted in full above. Read promptFeedback.blockReason before finishReason: five of these names are values of both enums and mean different things on each field. safetyRatings resolves SAFETY to a category on Google’s own instruction; citationMetadata resolves and also defines RECITATION; finishMessage is documented to be populated whenever a reason is set, with nothing documented about what it holds. For the remaining six, nothing in the five files we read distinguishes a cause, and the blocked content is not returned.
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