TEAL Versions

Each version of PyTeal compiles contracts for a specific version of TEAL. Newer versions of TEAL introduce new opcodes and transaction fields, so PyTeal must be updated to support these new features. Below is a table which shows the relationship between TEAL and PyTeal versions.

TEAL Version	PyTeal Version
1	<= 0.5.4
2	>= 0.6.0
3	>= 0.7.0
4	>= 0.8.0
5	>= 0.9.0
6	>= 0.10.0

In order to support TEAL v2, PyTeal v0.6.0 breaks backward compatibility with v0.5.4. PyTeal programs written for PyTeal version 0.5.4 and below will not compile properly and most likely will display an error of the form AttributeError: * object has no attribute 'teal'.

WARNING: before updating PyTeal to a version with generates TEAL v2 contracts and fixing the programs to use the global function compileTeal rather the class method .teal(), make sure your program abides by the TEAL safety guidelines https://developer.algorand.org/docs/reference/teal/guidelines/. Changing a v1 TEAL program to a v2 TEAL program without any code changes is insecure because v2 TEAL programs allow rekeying. Specifically, you must add a check that the RekeyTo property of any transaction is set to the zero address when updating an older PyTeal program from v0.5.4 and below.