GL_INVALID_OPERATION from draw call: glGetError returns it once, then GL_NO_ERROR — which command actually failed?

Question

An OpenGL 4.5 core-profile application (desktop, GLFW-created context) renders a scene with several draw calls, VAOs, and shader programs per frame. After a recent change, nothing appears on screen. Polling glGetError once per frame reports GL_INVALID_OPERATION a single time, then returns GL_NO_ERROR on every subsequent call, even though the failure persists visually.

The documentation describes error flags as sticky until queried, with one flag returned and cleared per call, and GL_INVALID_OPERATION covering many distinct state problems: drawing with an incomplete framebuffer, using a program that failed to link, or drawing without a bound VAO in a core context. That makes a single polled value ambiguous — it is unclear which command raised the flag, or whether multiple independent errors were queued and only the first was observed.

A debug context with glDebugMessageCallback is available as an option, but message presence and content are documented as implementation-dependent, so it is not clear how much to trust it across NVIDIA, AMD, and Mesa drivers.

Is a single glGetError result sufficient to conclude only one error occurred, or must the call be looped until GL_NO_ERROR to drain all pending flags?

What is the documented way to attribute GL_INVALID_OPERATION to the exact failing command rather than the frame in which it was polled?

Should GL_COMPILE_STATUS/GL_LINK_STATUS and glCheckFramebufferStatus be ruled out first, given they fail silently without setting a glGetError-visible draw-time fault?

Zoha · Answer

Direct answerA single glGetError call returns only the first pending error flag and clears it. Subsequent calls return the next queued error or GL_NO_ERROR. Therefore, one polled value cannot guarantee that only one error occurred, nor can it identify the offending command.Confirmed factsglGetError consumes and returns exactly one error flag per invocation.GL_INVALID_OPERATION aggregates many distinct state problems: missing or unbound VAO, inactive or unlinked shader program, incomplete framebuffer, or drawing in a core profile without a vertex array object.Program linking/compilation status and framebuffer completeness do not set glGetError-visual flags at draw time; they must be queried explicitly.Steps for this caseLoop glGetError until the return is GL_NO_ERROR to drain all pending flags in the current frame.Before each draw call, verify that a VAO is bound: glBindVertexArray the intended object.Query glGetProgramiv(program, GL_LINK_STATUS) and glGetShaderiv(shader, GL_COMPILE_STATUS) to confirm the active program is valid.Call glCheckFramebufferStatus(GL_FRAMEBUFFER) and ensure the result is GL_FRAMEBUFFER_COMPLETE.If a debug context is available, enable glDebugMessageCallback; driver-specific callback output is the most precise way to attribute GL_INVALID_OPERATION to a specific command, but treat it as debugging aid, not production error handling.Missing diagnostic detailDo you have a debug context enabled with glDebugMessageCallback? Enabling it will allow the callback to name the exact OpenGL command that generated the error, which can change the recommended diagnostic path from systematic state verification to direct attribution.

GL_INVALID_OPERATION from draw call: glGetError returns it once, then GL_NO_ERROR — which command actually failed?

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