The warning sign is buried in a technical chart tracking “missed slots”—digital moments where the Ethereum network simply blinked and failed to record a transaction block. After a major upgrade called Fusaka went live in late 2025, engineers expected a flood of new data to fill the expanded capacity. Instead, they found two unsettling surprises: the new space is mostly empty, and on the rare occasions it actually gets full, the system starts to stutter.
- Fusaka upgrade went live in late 2025.
- Target blob count raised from 6 to 14.
- Max error rate hits 1.79% with 21 blobs.
To understand what happened, we have to look at “blobs.” In the Ethereum network, a blob is essentially a specialized data container. Think of the main blockchain like a shared Google Doc that everyone can read but nobody can secretly edit. Storing data directly on the main page of that document is expensive because every computer in the network has to process it.
Blobs are a workaround. They are like sealed envelopes attached to the document. The network proves the envelope exists and hasn’t been tampered with, but it doesn’t force every computer to open and read the letter inside. This makes it much cheaper for Layer-2 networks—services that bundle thousands of transactions together—to post their records to Ethereum.
Building a wider highway
The Fusaka upgrade was supposed to be a simple expansion project. It was like a city deciding to widen a highway from six lanes to fourteen. The goal was to help those Layer-2 networks operate more cheaply and quickly.
Starting in December 2025, developers adjusted the settings. They raised the “target” number of blobs per block from 6 to 10, and eventually to 14. They also set a hard maximum of 21 blobs per block. The logic was sound: if we build it, the traffic will come.
But a report from MigaLabs shows the traffic didn’t show up. In fact, after the lanes were widened, the median number of blobs per block actually dropped from 6 down to 4. The network has massive amounts of “headroom”—empty space—that nobody is using.
The speed wobble
The lack of traffic might be embarrassing, but the real concern is what happens when traffic actually appears. The data shows that while the highway is empty, everything runs smoothly. But when the network tries to process a “full” block containing 16 or more blobs, things get shaky.
This is where those “missed slots” come in. A missed slot is like a dropped phone call; the network tried to connect a block of transactions to the chain, but it failed. Usually, this happens about 0.5% of the time—a tiny, manageable error rate.
However, when blocks are packed with 21 blobs (the new maximum), that error rate jumps to 1.79%. That might still sound low, but in a financial system that runs 24/7, a triple-digit increase in errors is a red flag. It suggests the infrastructure—the thousands of computers verifying these transactions—struggles to keep up when the pressure is high.
The price of empty space
There is also an economic twist to this story. Before Fusaka, if nobody wanted to send blobs, the price to send them would drop. And drop. And drop. Eventually, the price would hit near zero.
This sounds great for users, but it’s bad for the network. It’s like selling plane tickets for one cent; eventually, people buy seats just to put their luggage on them, clogging up the system with junk. It breaks the economic feedback loop.
Fusaka introduced a “reserve price floor.” This acts like a cover charge. Even if the club is empty, you still have to pay a minimum amount to get in. This ensures that the price of sending a blob never becomes meaningless. The data shows this is working: fees have stabilized, preventing the “race to the bottom” that engineers feared.
What happens next?
The conclusion from the analysts is straightforward: stop digging. The network shouldn’t try to expand capacity any further right now.
We are currently in a strange position. We have a system that is too big for the current demand, yet slightly too weak to handle the maximum theoretical load. If usage suddenly spiked and every block was full, we might see significant delays or instability.
For now, the best move is to wait. The infrastructure needs time to catch up to the new limits, and actual user demand needs to grow enough to justify the space that already exists. Until the “missed slots” return to normal levels during heavy traffic, making the pipes any bigger would be asking for trouble.
