FAQ

Common

• How to reuse a JsonBuffer?★★★★
• What are the differences between StaticJsonBuffer and DynamicJsonBuffer?★★
• What's the best way to use the library?★★
• How to determine the buffer size?★★
• Why shouldn't I use a global JsonBuffer?★
• How to reduce memory usage?★
• Why does my device crash or reboot?
• What are the common sizes for JsonBuffer?
• I found a memory leak in the library!
• How to assign a JsonArray or JsonObject?
• How to write a function that works with both JsonArray and JsonObject?

Deserialization

• Error: invalid conversion from 'const char*' to 'int' [-fpermissive]★★★★★
• Why parsing fails?★★★
• Can I parse a JSON input that is too big to fit in memory?★
• Error: invalid conversion from 'const char*' to 'char*' [-fpermissive]★
• The first parsing succeeds, why do the next ones fail?
• Can I parse data from a stream?
• How to iterate over a JsonVariant?
• Parsing succeeds but I can't read the values!
• Can I access to object member by its index, instead of its key?
• How to know the type of a value?
• Why is the input modified?

Known problems

• Error: Ambiguous overload for 'operator='★
• ESP32
• Error: undefined reference to __cxa_guard_acquire and __cxa_guard_release
• Warning: ignoring packed attribute because of unpacked non-POD field
• Atmel Studio
• Arduino Library Manager doesn't list the latest versions of ArduinoJson
• Error: 'equals' is not a member of 'ArduinoJson::Internals::StringTraits<const int&, void>'
• Sloeber Arduino Eclipse Plugin
• CodeBender
• Adafruit WICED Feather
• Warning: floating constant exceeds range of 'double'
• Arduino Zero, mkr1000 and all boards based on SAMD21
• Compilation fails after upgrading the library

Serialization

• How to create complex nested objects?★★
• Why ArduinoJson is slow?
• Using a loop, why are values all the same?
• How to insert a null?
• The first serialization succeeds, why do the next ones fail?
• How to compute the JSON length?
• How to prevent string escaping?
• Why are some parts missing?
• Why does the generated JSON document contain garbage?

Cannot find the answer?