Failed to synthesize text Resource has been exhausted (e.g. check quota).

[k0diak]

can someone tell me what happened and why it won't complete text to speech MP3s anymore?

[pgmichael]

You've most likely exceeded Google's API quotas.

There is some technical improvements that could be done to avoid this, so I'm going to leave the issue open. In the meantime, you can try again later and with a smaller selection/text.