-[EAGLContext renderbufferStorage:fromDrawable:] Failing the second time on?

I'm developing an iOS openGL ES application.

I'm doing the usual EAGLView / ES2Render stuff.

On startup, frambuffer creation succeeds, using the following code:

- (BOOL) createFramebuffers
{
    [EAGLContext setCurrentContext:_mainContext];

    // [ A ] On-screen  

    // 1. Framebuffer
    glGenFramebuffers(1, &_mainFramebuffer);
    bindFramebuffer(_mainFramebuffer);

    // 2. Color buffer
    glGenRenderbuffers(1, &_mainColorbuffer);
    bindRenderbuffer(_mainColorbuffer);

    // Adjust size to view's layer:
    CAEAGLLayer* layer = (CAEAGLLayer*)[_view layer];

    if (![_mainContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer]) {
        // something went horribly wrong
        NSLog(@"-[ES2Renderer createFramebuffers]: Failed to obtain renderbuffer storage from layer!");
        return NO;
    }

    // Query new size:
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH,  &_backingWidth);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &_backingHeight);

    // Attach to color:
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _mainColorbuffer);

    // 3. Depth buffer
    glGenRenderbuffers(1, &_depthBuffer);
    bindRenderbuffer(_depthBuffer);

    if (_useStencilBuffer) {
        // Depth + Stencil

        // Allocate storage:
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);

        // Attach to depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _depthBuffer);

        // Attach to stencil:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _depthBuffer);
    }
    else{
        // Depth only

        // Allocate storage:
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);

        // Attachto depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _depthBuffer);

    }

    // 4. Validate the set:
    GLenum framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);

    if (framebufferStatus != GL_FRAMEBUFFER_COMPLETE) {
        // Something went wrong!

        NSLog(@"-[ES2Renderer createFramebuffers]: Failed to make complete framebuffer object: %@",
              [self stringFromFramebufferStauts:framebufferStatus]);

        return NO;
    }

    // [ B ] Off-screen (Render-to-texture)

    // 1. Framebuffer
    glGenFramebuffers(1, &_transFramebuffer);
    bindFramebuffer(_transFramebuffer);

    // 2. Depth buffer
    glGenRenderbuffers(1, &_transDepthBuffer);
    bindRenderbuffer(_transDepthBuffer);

    if (_useStencilBuffer) {
        // Allocate storage:
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);

        // Attach to depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _transDepthBuffer);

        // Attach to stencil:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, _transDepthBuffer);
    }
    else{
        // Allocate storage
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);

        // Attach to depth:
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _transDepthBuffer);
   }


    // 3. Textures (color buffers)

    GLuint* texPtrs[2] = {&_transTexture1, &_transTexture2};

    for (NSUInteger i=0; i < 2; i++) {

        GLuint* texPtr = texPtrs[i];

        // Create:
        glGenTextures(1, texPtr);

        // Bind:
        bindTexture2D(*texPtr);

        // Configure for pixel-aligned use:
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        // Allocate storage:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, _backingWidth, _backingHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

        // Attach:
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, *texPtr, 0);

        framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);

        // Validate:
        if ( framebufferStatus != GL_FRAMEBUFFER_COMPLETE) {
            // Something went wrong!

            NSLog(@"-[ES2Renderer createFramebuffers]: Failed to make complete framebuffer object: %@",
                  [self stringFromFramebufferStauts:framebufferStatus]);

            return NO;
        }
    }

    // Final State:

    bindFramebuffer(_mainFramebuffer);
    bindRenderbuffer(_mainColorbuffer);
    bindTexture2D(0);


    NSLog(@"-[ES2Renderer createFramebuffers] Succeeded.");
    return YES;
}

Soon after, UIView's -layoutSubviews is called and I in turn execute -resizeFromLayer::

- (BOOL) resizeFromLayer:(CAEAGLLayer *)layer
{
    // [ A ] On screen framebuffer

    bindFramebuffer(_mainFramebuffer);

    // 1. Resize color buffer
    bindRenderbuffer(_mainColorbuffer);

    if (![_mainContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer]) {
        // Something went wrong
        return NO; // <-- SECOND TIME ON, THIS HAPPENS
    }

    // Query new size:
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH,  &_backingWidth);
    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &_backingHeight);

    // 2. Resize depth buffer
    bindRenderbuffer(_depthBuffer);

    if (_useStencilBuffer) {
        // (Depth & Stencil)

        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);
    }
    else{
        // (Depth only)

        glRenderbufferStorage(GL_FRAMEBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);
    }

    // ...Validate:
    GLenum framebufferStatus = glCheckFramebufferStatus(GL_FRAMEBUFFER);

    if (framebufferStatus != GL_FRAMEBUFFER_COMPLETE) {
        // Something went wrong!

        NSLog(@"-[ES2Renderer resizeFromLayer:]: Failed to make complete framebuffer object: %@",
              [self stringFromFramebufferStauts:glCheckFramebufferStatus(GL_FRAMEBUFFER)]);

        return NO;
    }

    // [ B ] Off screen (render-to-terxture) framebuffer

    bindFramebuffer(_transFramebuffer);

    // 1. Resize depth buffer

    bindRenderbuffer(_transDepthBuffer);

    if (_useStencilBuffer) {
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, _backingWidth, _backingHeight);
    }
    else{
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, _backingWidth, _backingHeight);        
    }


    // 2. Resize textures

    GLuint* texPtrs[2] = {&_transTexture1, &_transTexture2};

    for (NSUInteger i=0; i < 2; i++) {

        GLuint* texPtr = texPtrs[i];

        // Bind:
        bindTexture2D(*texPtr);

        // Configure for pixel-aligned use:
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        // Allocate storage:
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, _backingWidth, _backingHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

        // Attach:
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, *texPtr, 0);


        // Validate:
        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
            // Something went wrong!
            NSString* statusString = [self stringFromFramebufferStauts:glCheckFramebufferStatus(GL_FRAMEBUFFER)];
            NSLog(@"-[ES2Renderer resizeFromLayer:]: Failed to make complete framebuffer object: %@", statusString);
            return NO;
        }
    }

    bindFramebuffer(_mainFramebuffer);
    bindRenderbuffer(_mainColorbuffer);


    // Pass new ortho projection to shaders
    [self initializeModelViewMatrix];
    [self initializeSpriteProgram];

    // Set new viewport
    glViewport(0, 0, _backingWidth, _backingHeight);

    NSLog(@"-[ES2Renderer resizeFromLayer:]: Succeeded.");

    return YES;
}

Nothing of what I'm doing is special. I have a separate framebuffer to render scene transitions, with two textures to attach to color, and depth.

The second time -renderbufferStorage:fromDrawable: is called (-layoutSubviews -> resizeFromLayer:), it invariably fails (returns NO); Calling glGetError() right before that results in no error, but calling it right after returns GL_INVALID_OPERATION. If I ignore this and proceed, glGetRenderbufferParameteriv() still gets me the right width and height (640 and 1136, respectively, on an iPhone 5), but glCheckFramebufferStatus() will return GL_FRAMEBUFFER_UNSUPPORTED.

Alternatively, I skipped the above resizeFromLayer: and replaced it with this:

- (BOOL) resizeFromLayer:(CAEAGLLayer *)layer
{
    [self destroyFramebuffers];

    return [self createFramebuffers];
}

...but the same error persists (-renderStorage:fromDrawable: fails; this time inside -createFramebuffers).

For now, I just return YES (my app only supports portrait, so no screen size change actually ever happens), but I really want to fix it because one day I'll need to support landscape, etc...

One possible reason that renderbufferStorage:fromDrawable: is failing is that the _mainContext is not the current context at that time. Even though it may seem that no other context could have stolen the 'current' status, I recommend calling [EAGLContext setCurrentContext:_mainContext] before any gl or EAGL code that operates on objects associated with that context (e.g. at the beginning of the resizeFromLayer: method).