Posting a tweet sometimes fails with the error "Over capacity"

[cygnan]

app[worker.1]: [main.py:34] @cygnan: "@twiwordcloudbot vscode オレンジ"
app[worker.1]: [main.py:62] Searching "vscode オレンジ"...
app[worker.1]: [main.py:74] -> 40 tweets were found.
app[worker.1]: [main.py:97] Doing morphological analysis using MeCab...
app[worker.1]: [main.py:119] -> Done.
app[worker.1]: [main.py:127] Generating a wordcloud image...
app[worker.1]: [main.py:134] -> Saved a wordcloud image to "/tmp/931490221622927361.png"
app[worker.1]: [main.py:144] [line 140] [{u'code': 130, u'message': u'Over capacity'}]
app[worker.1]: [main.py:151] Tweeted "@cygnan 500 Internal Server Error. Sorry, something went wrong."