Prevent EmitterException when output buffer has content#73
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If headers have not been sent but the output buffer is not empty, Laminas SapiEmitter throws an EmitterException. This commonly happens in WordPress when plugins (like Gravity Forms) leak output early. We now detect this scenario, clean the buffer, and echo its content before calling SapiEmitter, ensuring all previous output is preserved while allowing the PSR-7 response to be emitted correctly.
tommitchelmore
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May 20, 2026
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Looks good - one minor tweak. I've tried these changes in a downstream project and they seem to make the emitter much more resilient as intended.
Co-authored-by: Tom Mitchelmore <tommitchelmore@outlook.com>
richstandbrook
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May 20, 2026
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If headers have not been sent but the output buffer is not empty, Laminas SapiEmitter throws an EmitterException. This commonly happens in WordPress when plugins (like Gravity Forms) leak output early.
We now detect this scenario, clean the buffer, and echo its content before calling SapiEmitter, ensuring all previous output is preserved while allowing the PSR-7 response to be emitted correctly.