Improving error bypass method on keys in json

Question

The current method I use is as follows and this amount of try except is making me very uncomfortable and without confidence in the quality of using this method:

for post_message in json_data['result']:
    try:
        message_text_1 = post_message['channel_post']['caption']
        print('Image: ' + message_text_1)
    except:
        try:
            message_text_2 = post_message['channel_post']['pinned_message']['text']
            print('Pinned Message: ' + message_text_2)
        except:
            try:
                message_text_3 = post_message['channel_post']['pinned_message']['text']
                print('Basic Text: ' + message_text_3)
            except:
                pass

I tried using if not and elif not but it throws KeyError when it doesn't find the key instead of going to the next step:

for post_message in json_data['result']:
    if not (post_message['channel_post']['caption'] is None):
        message_text = post_message['channel_post']['caption']
        print('Image: ' + message_text)

    elif not (post_message['channel_post']['pinned_message']['text'] is None):
        message_text = post_message['channel_post']['pinned_message']['text']
        print('Pinned Message: ' + message_text)
        
    elif not (post_message['channel_post']['pinned_message']['text'] is None):
        message_text = post_message['channel_post']['pinned_message']['text']
        print('Basic Text: ' + message_text)

And I also tried using except KeyError but besides it doesn't understand the first except, the second except is disabled:

for post_message in json_data['result']:
    try:
        message_text = post_message['channel_post']['caption']
        print('Image: ' + message_text)
    except KeyError:
        message_text = post_message['channel_post']['pinned_message']['text']
        print('Pinned Message: ' + message_text)
    except KeyError:
        message_text = post_message['channel_post']['pinned_message']['text']
        print('Basic Text: ' + message_text)

What would be the most correct model to work with when there is more than a chance that the key does not exist in the JSON?