Answered

DecodeBase64 is Not Working For Me

(0) Share

Report

Posted on by Community Power Pla... Microsoft Employee

Hi all,

I am trying to build a flow that converts a Bearer token into a string I'm using the decodeBase64 method, but my Flows continue to fail at the step decodebase64 below is an error.

but the base64 string is get decoded on https://www.base64decode.org

Unable to process template language expressions in action 'Compose_3' inputs at line '0' and column '0': 'The template language function 'decodeBase64' was invoked with a parameter that is not valid. The value cannot be decoded from base64 representation.

Base64string is:

eyJpYXQiOjE2NzY0MzMyMTMsInZlciI6IlNUSS5FeHRlcm5hbEFjY2Vzc1Rva2VuLlYxIiwiYXBwaWQiOiI0OGFmMDhkYy1mNmQyLTQzNWYtYjJhNy0wNjlhYmQ5OWMwODYiLCJzdWIiOiJTYXVyYWJoLlRyaXBhdGhpQGhhdmVsbHMuY29tIiwiYXBwaWRhY3IiOiIyIiwiYWNyIjoiMCIsInRpZCI6IjdiN2RjMmY1LTRlNmEtNDAwNC05NmRkLTZjNzkyMzYyNWIyNSIsInNlbmRlciI6IlNhdXJhYmguVHJpcGF0aGlAaGF2ZWxscy5jb20iLCJvaWQiOiI4OTE2YjY1Zi00YTAzLTRmZmItOGFiNC0xNDdhOWViODc5NGYiLCJuYmYiOjE2NzY0MzMyMTMsImV4cCI6MTY3NjQzNDExMywiaXNzIjoiaHR0cHM6Ly9zdWJzdHJhdGUub2ZmaWNlLmNvbS9zdHMvIiwiYXVkIjoiaHR0cHM6Ly9wcm9kLTAzLmNlbnRyYWxpbmRpYS5sb2dpYy5henVyZS5jb20ifQ

The concerned section of my flow looks like this:

Is there something wrong with my syntax?

please help!!

Categories:

Building flows

I have the same question (0)

All responses (5)

Answers (1)

Community Power Pla... Microsoft Employee on at

Like (0)

Report
Copy link

Link copied!

@Chriddle, need your expert views on this.

Was this reply helpful? Yes No
Community Power Pla... Microsoft Employee on at

Like (0)

Report
Copy link

Link copied!

@v-yuazh-msft, need your expert views on this.

Was this reply helpful? Yes No
Verified answer

Chriddle 8,672 Super User 2026 Season 1 on at

Like (5)

Report
Copy link

Link copied!
Your base64 string is missing the padding (character[s] "=" added to make the last encoded block contain 4 characters)
Try this to add them (assuming your encoded string is in "Compose"):

decodeBase64( if( equals( mod(length(outputs('Compose')), 4), 1 ), concat( outputs('Compose'), '===' ), if( equals( mod(length(outputs('Compose')), 4), 2 ), concat( outputs('Compose'), '==' ), if( equals( mod(length(outputs('Compose')), 4), 3 ), concat( outputs('Compose'), '=' ), outputs('Compose') ) ) ) )

3 people found this reply helpful.

Was this reply helpful? Yes No
Chriddle 8,672 Super User 2026 Season 1 on at

Like (0)

Report
Copy link

Link copied!

The test for (mod 4 == 1) is superfluous, this cannot happen.

Was this reply helpful? Yes No
KurtisRC 21 on at

Like (0)

Report
Copy link

Link copied!

Thank you, I've been trying to work this out for 48 hours.
You are amazing, thank you sooooo much.

Was this reply helpful? Yes No