> For the complete documentation index, see [llms.txt](https://docs.zerve.ai/zerve-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zerve.ai/zerve-docs/compute/troubleshooting-block-runs.md).

# Troubleshooting block runs

What common block run errors mean, and how to fix them.

## A block run timed out

You'll see: `Block run has timed out.`

The block ran longer than its compute type allows.

**On Lambda**, blocks are limited to **15 minutes**. Switch the block to **Fargate** in its compute settings, which can run for up to 12 hours.

**On any compute**, block runs are limited to **12 hours**. Split the work into smaller blocks, or use [Fleet](/zerve-docs/compute/fleet.md) to run parts of it in parallel.

## A Lambda block ran out of memory

You'll see: `Lambda has run out of memory.`

The block needed more than Lambda's **10 GB** of memory. Switch it to **Fargate**, which can have up to 120 GB.

## A Fargate block ran out of memory

You'll see: `Block run ran out of memory. Consider increasing memory for your Fargate block in settings.`

The block needed more memory than it was given. Choose a larger size in the block's compute settings, up to 120 GB. If it needs more than that, process the data in smaller pieces, or use [Fleet](/zerve-docs/compute/fleet.md) to split it across parallel runs.

## A GPU block can't start

The run failed because no GPU was available. Cloud GPU capacity isn't guaranteed. Turn on **Retry until GPU is available**, choose a different instance type, or try again later. See [GPUs](/zerve-docs/compute/gpus.md).

## A GPU block is slow

The block may not be using the GPU, because its environment doesn't include GPU-enabled libraries. Use the **Deep Learning (CUDA 12.6)** preset or add GPU versions of your libraries. See [Environment presets](/zerve-docs/environments/environment-presets.md).

## A block hasn't started

You or your organization are at the [concurrency limit](/zerve-docs/compute/limits-and-concurrency.md#concurrency), so the run is waiting in a queue. It starts when other runs finish.

## A block can't connect to a database

If your database only accepts connections from approved IP addresses, it may be blocking Zerve. Check your connection settings, and ask your Zerve administrator for the fixed IP address to allow. If your organization runs Zerve in its own AWS account, the address is your account's outbound IP. See [AWS QuickStart](/zerve-docs/self-hosting/aws-quickstart.md).

## A package is missing

The block's environment doesn't include a package the code imports. Add it to the environment. See [Environments and packages](/zerve-docs/environments/environments.md).

## A run can't be stopped

On some compute types, a run that hasn't actually started yet can't be stopped until it does. Zerve tells you when this happens; try again once it's started.


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