[ic] [timed-build] causes ".... Failed to create StaticDBM" error

[DB]

IC 4.8.7

I'm using the [timed-build] tag on a "site index" page which lists some 
of my products. The tag appears to be working... files get created in 
the tmp/auto-timed folder and these files appear to be getting used as 
expected. However in my catalog's error.log I'm seeing messages such as

....Failed to create StaticDBM

Below is the hunk of code from the page. Can anyone tell me what if 
anything is wrong? Thanks for any info.

DB

--------------------

[timed-build auto=1 force=1 minutes=0]
[search_region more=1 search="
                  ra=yes
                  st=db
                  fi=products
                  tf=sku
                  fm=1001
                  ml=500
                  "]
[search_list]

<A HREF="http://__SERVER_NAME__/[item-code].html">
                 [item-field sku] </A>: [item-field description] 
[item-field comment]
<hr>
[/search_list]

<br>

[/search_region]
<small>
Built [time]%c[/time]
</small>
[/timed-build]

-------------------