Conditional {if} and {if:else} Getting Error Message

Question

I get an error message each time. "You have an invalid conditional in your template. Please review your conditionals for an unclosed string, invalid operators, a missing }, or a missing {/if}." Stuck not sure what to do.

  {exp:channel:entries channel="{segment_1}"}
     {if banner}
     <img src="{banner}" alt="photo:{title}" class="margin-top-minus-20 img-responsive osd-border" />
     {/exp:channel:entries}
     {if:else}
      <!-- snippet-->
     {snp-banner-grid}{/if}

Answer 1

{exp:channel:entries channel="{segment_1}"}
     {if banner}
        <img src="{banner}" alt="photo:{title}" class="margin-top-minus-20 img-responsive osd-border" />
     {if:else}
        {snp-banner-grid}
     {/if}
{/exp:channel:entries}

Answer 2

You cannot close your exp:channel:entries-tag in a branch of the if-structure, because in case you have a banner (first branch) you finish the channel-loop and will not get to the end of the if-construct. Vice versa if you do not have a banner you will not end the channel-loop.

Therefore put the closing {/exp:channel:entries} after the very end of your code snippet and it will work.