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AuthError 'invalid_access_token' with Python SDK after Token Refresh

Dear Dropbox Developer Team,

I have been using the Dropbox API with your Python SDK for approximately four years without any issues. However, since November 25th or December 1st, I started encountering AuthError exceptions related to invalid access tokens. My implementation has remained unchanged during this time.

I store tokens in a database and update them whenever the SDK retrieves a fresh one. Here is the relevant code snippet:

After refreshing the access token using check_and_refresh_access_token(), subsequent requests (such as to files_list_folder or files_get_temporary_link) proceed without issue. However, when a new instance of DBXManager is created and the token is still valid (i.e., not expired and therefore not refreshed), requests may fail with the following error:

dropbox.exceptions.AuthError: AuthError('a5dae06f271b404296dc9d254e75eb47', AuthError('invalid_access_token', None))

The only way to resolve this issue is to refresh the token again. As a temporary workaround, I am manually adjusting the token expiration in the database to force a refresh on the next instance creation.

I am trying to understand the root cause of this behavior:

Was there any recent change to the Dropbox backend or API behavior that could explain this issue?
If this is a problem on my end, could you help clarify why the same implementation worked flawlessly for years?

Thank you for your assistance. Please let me know if you need additional details about my setup or logs.

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Accepted answers

Greg-DB

I see our messages just crossed, but yes, it sounds like that's the issue. The access tokens can certainly be longer than 255 characters, and you may have only recently started receiving access tokens of that length, so a database limit like that would cause the issue.

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qpo

Only after posting this, I had an idea—could the issue be related to token length? It seems that the token length may have changed recently, and I suspect it might no longer fit into my database's varchar(255) column.

If I do not update this thread, it can be treated as solved by increasing the size of the field that stores tokens.

Greg-DB

It sounds like your database may be corrupting the access token, causing the subsequent API calls using the retrieved corrupted access tokens to fail. In particular, might your database have a length limit for storing the access tokens, which effectively truncates them?

Note that Dropbox API access tokens can vary in length, and you may have started receiving longer ones, potentially recently exceeding whatever the length limit is for your storage.

There isn't a guaranteed maximum length for Dropbox API access tokens, so make sure you're storing them via a method without a maximum length.

Greg-DB