o small then olm_account_last_error() will be &quot;NOT_ENOUGH_RANDOM&quot;.</p></dd></dl><dl><dt class="spec value" id="val-account_fallback_key_length"><a href="#val-account_fallback_key_length" class="anchor"></a><code><span class="keyword">val</span> account_fallback_key_length : <span><a href="../Types/Account/index.html#type-t">Types.Account.t</a> Ctypes_static.ptr</span> <span>&#45;&gt;</span> Unsigned.size_t</code></dt><dd><p><code>account_fallback_key_length acc</code></p><p>The number of bytes nee